DPS In a Nutshell
DPS stand for Damage Per Second and it's the "per second" bit that confuses a lot of players who are new to MMOs or the role in general. They see a single 5,000-point hit and think that's "wicked DPS" when in reality that single hit means almost nothing to their actual performance.
It's the "per second" part that actually determines your performance. Big hits are great, but unless they come fast enough you're not really doing your job.
You could do 1 million damage to a boss, which sounds awesome!
But if it took you 30 minutes to do that million, you only did a piddly 555 DPS.
DPS is the amount of damage you've done divided by the length of the fight in seconds. Think of damage like distance; DPS would be your speed. You could travel a long distance but if you're too slow about it you're not doing it efficiently.
It's critical to take time into account because most bosses in TOR have some sort of Enrage mechanic that pressures the group into killing it within a certain timeframe. (Without an enrage, it would be possible to take less DPS and more tanks or healers in your group, which would increase your survivability but make fights take forever.) There are two types of enrages: hard and soft.
A Hard Enrage is a timer that ticks down from when the boss is first pulled; when it expires the boss turns red and gets a buff that magnifies the damage it puts out, usually resulting in a dead tank and after that, a group wipe. Timers are different for every boss. Some enrages are worse than others; it's entirely possible to tank Soa in EV for an absurdly long time after his enrage because his base damage is rather low and he hits infrequently. But the Annihilation Droid in EV can wipe a group of level 55s in seconds if he enrages during his Missile Volley.
A Soft Enrage is similar, but instead of the boss getting a straight damage buff, something happens to the boss or the environment that makes it difficult to continue. An example is the droid boss in Lost Island: if you take too long, the room fills up with lava and all his electric bubbles shoot out at full size.
Avoiding the enrage is the responsibility of every DPS player in the group. There are separate failure cases for tanks and healers, but if a boss enrages: it's ultimately the fault of the DPS.
So how to go about squeezing all the DPS you can out of your characters? Like tanking and healing performance, DPS is a combination of gear and player input/skill. The better geared your character, the more DPS he can put out; however player skill is actually much more important. It's possible, even likely, that a higher skilled player wearing inferior gear can out-DPS a lower skilled player wearing far superior gear.
I won't go into much detail about gear in this guide. For general advice, check out Gearing Up in SWTOR. For class specific gear recommendations, check your class guides on these forums.
However, I can tell you that the most important pieces of gear are your Mainhand Weapon, and Offhand. More specifically, the Barrel or Hilt in your mainhand and the Barrel/Hilt/Armoring in your offhand, because those two mods are what determines your Melee or Ranged damage and your Force or Tech power. Those two mods should be a top priority for upgrades.
Also, be sure that you are not equipping ANY gear or mods with the following stats:
These are TANKING stats, and do nothing to increase DPS. Every point of those stats on your gear is a point that could be spent on a DPS stat like Accuracy, Crit, Power, or Surge.
Also, be wary of Alacrity. It reduces cast times and slightly shortens the Global Cooldown, but you have to stack tons of it to see even a 5-10% benefit and every point of Alacrity is one point less of Accuracy or Surge, which are far more important stats for DPS. Try to get it off your gear ASAP and replace it with those stats instead.
Generally speaking, your top gearing priority (aside from getting the best mainhand available) is to get your Accuracy to 100%(ranged/melee) (which will also set your force/tech accuracy to 110%). Depending on your class's talent trees you might get there with 400 points of Accuracy, or it might take 450 or more. But get there. Once that's done, use Surge enhancements/implants/earpieces. Then stack power.
When picking Augments, it's generally advisable to use either Overkill (Power) augs or whatever your main stat is:
Aim -> Reflex
Strength -> Might
Willpower -> Resolve
Cunning -> Skill
Power gives you a sliiiiiiightly better bump to your damage than Main Stat (something like 1.2 compared to 1.1), but Main Stat contributes to your critical chance and power doesn't. If your class/spec has access to a talent that gives a +% increase to your main stat, it's usually a good idea to take that and use main stat augments, as the % boost will narrow the gap with Power and increase your crit rate.
(I'm fairly sure that the only classes that do not have access to such a talent, and thus are better off with Overkill augments, are Sentinels and Shadows.)
APM stands for Actions Per Minute and it is usually the place where I see a lot of new players struggling to increase their DPS. Put simply, there are a limited number of skills you can use in a given period of time, so if you are using less than that number you are hindering your potential DPS.
The simplest ways to increase your APM are to Know Your Rotation, and Don't Introduce Delay.
Know Your Rotation
A rotation is the pattern of skills you activate in a particular order depending on your class, talent tree, and nature of the fight. It is always, always more effective to use a rotation as opposed to randomly mashing whichever buttons are off cooldown. Every class and spec is going to have a different rotation, and some are simpler than others. The simplest are essentially using skills A through G in a row, then starting over at the beginning. The most complicated are not really rotations at all, but priority systems that dictate which skills you should use more often than others. As usual, check with your individual class guides for feedback on optimal rotations or priority systems.
The key thing that learning your rotation will do for you is get you in the habit of knowing which skill you need to use next. Some skills are best used after you apply a particular debuff to the enemy, or apply a buff to yourself. Some do far more damage than others no matter what, so you should use them every time they come off cooldown and/or you have the resources available to activate them. Like a chess master, you should always be thinking ahead, to the next couple of skills. Knowing what you need to use next will help you eliminate delays and increase your APM.
Don't Introduce Delay
So you've got your rotation set, that's all that's needed for great DPS, right? WRONG! You still need to run through that rotation, and the speed with which you do it is going to ultimately determine your overall DPS. You can do your rotation perfectly and still be far from optimal efficiency simply because you introduce delays between your skills.
Take Alice and Bob for example. Alice and Bob both run the same class, same spec, wear the same gear, and use the same rotation. Alice chains her skills together with no delay. But Bob takes his time and introduces a measly half-second delay between all his skills. The result? Bob is only doing 75% of Alice's DPS. Their gear and stats are equal, but Alice is outperforming Bob simply by getting in ten more attacks per minute.
This is why it is absolutely critical that you use your skills as quickly as possible.
You may notice that once you start increasing the frequency of your skill uses, that your resource management becomes more difficult. You might be dropping low on Force/Ammo/Energy like you didn't before. This is a good thing! Learning how to manage your resources while still pushing your DPS to the limits is an important part of growing as a player. I often hear people with low DPS mention things like, "I never have any resource problems." All I can think in that case is, "Well you obviously aren't pushing hard enough." (Unless you're a TK Sage, which actually DOES never have resource problems!)
The Global Cooldown and You
The Global Cooldown is the ability delay inserted by the game after most skills. It's the gray bar that covers all your skills and melts away quickly, during which time you can't use (most*) other skills. By default the GCD is 1.5 seconds long, but can be shortened with Alacrity buffs or gear. (Don't gear for Alacrity!)
There are three types of skills in TOR:
1. Instant skills: activate as soon as you hit the button. Trigger the GCD when activated.
2. Cast time skills: Charge up for a few seconds (bar fills up towards the right) at which point the skill fires. They trigger the GCD when you hit the button, not when the skill fires. If you move you break the cast.
3. Channeled skills: Activate immediately, and stay active while the cast bar drains (to the left). Trigger the GCD at the start. Moving breaks the channel and puts the skill on cooldown.
Instant skills are the only ones that introduce a mandated 1.5 second delay AFTER the skill is over. You don't notice the GCD during Cast and channeled skills because it's going on while the skill is activating or channeling, and once they're done you can fire another skill immediately with no delay.
I bring this up because instant and cast-time skills allow you to queue your next skill - basically put it in line to fire as soon as your current skill and any GCD is done. By default TOR sets the skill queue time as 0.5 seconds, so hitting another skill during the last 0.5 seconds of a cast or GCD will trigger the 2nd skill to fire automatically when the cast or GCD is finished. Less delay = More APM!
(Ability queue time can be set from zero to 1 second in Preferences > Controls > Combat options)
However! Activating any other ability while a channeled skill is running, will break the channel and start the 2nd skill immediately. You want to avoid doing this, because your channeled abilities push out damage every second, with a final tick at the very end of the channel. Breaking the channel sacrifices that last damage tick (which in some cases, like Master Strike, is more damaging than the other ticks). Likewise, try not to move while channeling or you will cut your skill short and lose damage.
*Certain skills are "off the global cooldown" and can be activated at any time, whether or not the GCD is in place. These are useful for "breaking" the GCD and squeezing out more APM than you would otherwise be able to do.
Mandatory UI Settings
There are a few UI settings which all DPS (and really, everyone who is serious about group content) should enable.
The first is Target Castbar, which tells you when your selected target is casting or channeling an ability. Use the interface editor to increase the scale of this element - make it big so it's impossible to miss when it pops up. Bosses often have hard-hitting abilities with cast bars, so it's important to know when they are about to go off so you can either help interrupt it, or get out of the way.
Next is Target of Target, which shows you which target YOUR target is engaged with. This will tell you when the boss switches aggro from the tank onto you (good time to use your threat dump ability!) or when you're trying to peel an add off the healer.
Focus Target: hitting Alt-F while something is targeted locks that player or enemy in as your Focus Target, which hangs in the middle of your screen. It's handy for not losing track of a boss while dealing with adds. There's also a Focus Target Castbar, which you should scale up to max. That will help alert you if the important target is casting something dangerous while you're off dealing with adds.
Preferences > Controls > Camera -- Set Camera Max Distance all the way to 100%. This will let you zoom out to a proper distance so you have exponentially better situational awareness.
Preferences > Combat Logging > Enable Combat Logging to File -- this will activate combat logging, allowing you to use MOX and other parsing programs to analyze your performance.
Preferences > Graphics > Advanced -- Set Visible Character Limit as high as possible. There are a lot of operations encounters, especially in 16-man size, that have MANY MANY active enemies. If this setting isn't high enough, some of them will not appear for you!
Now that the DPS theory is out of the way, on to some DPS Best Practices
A lot of this is going to be summations of discusion from Group Tactics 101 so bear with me.
1. Kill Order: Weakest to Strongest by default, unless there are healing mobs present, in which case CC/kill/interrupt/stunlock them first of all. You will better protect the group by killing all the little weak and normal adds right away, instead of wailing on the Elites/Champs that take forever to kill while those normals all chew up your tank/healer.
1. Yeah, I can see there's two number ones. That's because this is equally important. FOCUS FIRE. When wailing on big targets, don't be doing your own thing while the rest of the group is doing another. Gang up on enemies with the whole group so they die quicker, then move on to the next. It helps your healers by reducing incoming damage on the group faster than if everybody is hitting their own mob. It helps the tanks because they can't hold aggro on a bunch of mobs when everybody's hitting something different. FOCUS FIRE, BITCHES.
2. Don't break CC. Be careful when AOEing around CC'd mobs because your abilities often hit things a lot further away than you anticipated. Double Saber Throw is notorious for pulling a group on the dark side of the ing moon with its range. Your ground target circles are often much, much smaller than the actual radius of damage. Force Quake hits everything on the god damn planet. When it's imperative that something stay mezzed, and the group leader calls "No AOEs!" he means PRECISELY THAT. Do not AOE, or the group may wipe and it'll be your fault.
3. Quit knocking shit out of the AOE. I know Noxxic tells you to use Force Wave for AOE damage. Don't use knockbacks when we have a pile of mobs bunched up for AOE damage. You will piss off everybody in the group.
4. Don't Stand in Shit. See a glowy yellow-white circle on the ground? It's a Salvation, go stand in it for heals. Any other color? GET THE OUT. Yeah, I know you're in the middle of a channel. Too bad. Yeah, I can see you're in cover. Too bad. Move your ass or your healers will forget about you.
5. Use your utility skills. Group buffs, cleanses, off-heals, stuns, even the occasional taunt can all be situationally useful. Go through your skill panel and read the description of every skill all over again. Then do the same for every talent in your talent tree. You may have missed something useful or important while leveling. I know very experienced players who never knew Skill X was good in Case Y even after they were at the level cap.
6. (Almost) Every skill is useful. I can probably count on one hand the number of skills I don't have on some toolbar, somewhere. Across all 11 of my characters. There are exceedingly few skills which are "useless." Many may be sub-optimal for a given build or role, but that just means you can hide them on toolbar 5 or 6 in case they're needed sometime.
7. Help out the tank. See an add wailing on the healer? Give it a few whacks until your target-of-target shows it's on you, and either kill it or drag it over to the tank so he can pick it up.
8. Help out the healer. Don't stand in front of enemies, especially bosses. They often have frontal AOEs that do a ton of damage. Stay behind them to be safe.
9. Abuse your threat dump. Every class has an ability that "reduces threat to all enemies." If mobs are aggro'd to you and you don't want the attention, use that dump! If the boss turns to you, use that dump!
10. Look at the enemy's buffs. Mouse over them shits. There's important information there, like whether or not it can be CC'd or knocked back. Or whether it's currently got a shield up that reflects all your damage back onto YOU. Or whether it is currently invincible and all the skills you're throwing at it are doing NOTHING.
Now let's talk about resources, because it's something that came up recently and it's a commonly misunderstood principle of good DPS.
It has long been my DPS philosophy that If you don't have resource problems, you're not pushing hard enough. Essentially, if your resource bar is always full or nearly full, and you never find yourself worrying about being low on Force/Ammo/Energy/Focus, you are doing it wrong.* I often hear people say "I never have resource problems" and in almost every case they are doing sub-par DPS. The exceptions are the players who know precisely what they are doing and are able to ride the sweet spot of resource loss/gain.
This game, like most other MMOs, is based around high-damage abilities that consume resources (or consume more resources than low damaging abilities). In order to put out the best DPS possible, you need to spend resources on high damaging skills. Then you need to either build resources with low damaging skills (Knights) or regen resources over time (Consulars, Smugglers, Troopers).
The trick to it is that you need to balance the resource drain from your high damaging abilities with your class mechanics for recovering resources. A character with no resources isn't going to be able to activate his best skills, but a character who is constantly at full resources clearly isn't using his best skills enough.
Playing too conservatively (hoarding resources so they're always full) is just as bad as playing too recklessly (burning all your resources and having to slowly build up from scratch). One of our intrepid Sentinels learned this a couple weeks back. He was using too many low-damage Focus builders in his rotation, and not enough high-damage Focus spenders. His Focus bar was almost always full, and he wasn't doing competitive DPS. When he started prioritizing abilities that dumped Focus and only built it up when it was needed, his DPS jumped almost 400 points.
Ultimately the job of a DPS is to turn their resource bar into damage in the most efficient way possible. Each class has a different method of spending and rebuilding their resource, but the principle remains the same. You need to avoid blowing all your resources at once, but neither can you hoard them because your DPS suffers in both cases. You need to find the sweet spot in your rotation where you're doing the max damage while maintaining a steady amount of resources so they're ready when you need them. You need to pay attention to the mechanics of your class (and spec, because some specs have wildly different resource regen triggers from other specs of the same class). Learn about every possible way your class can gain resources, whether it's regen over time, proc on incoming or outgoing damage, or a specific cooldown skill, and leverage those sources carefully so you don't waste resources.
DPS In a Nutshell