While I spend most of my WoW time tanking as a Paladin, I do have a Retribution secondary spec for my character. While this is mainly for PvP, I sometimes DPS on those occasions when another guild member is tanking.
I have found that the Retribution Paladin nicely fits my play style and attitude: I like a combination of good damage, good utility and excellent survivability. While a Retribution Paladin cannot match the AOE damage of a mage or the DOT abilities of a Warlock, they can put out impressive DPS-especially against single targets (like bosses). Also, the combination of plate armor, self healing and various defensive abilities make paladins survivors. As many WoW players have said “If you don’t like dying, play a paladin.”
In terms of optimizing your character, it is hard to beat Elitist Jerks’ number crunching and theory crafting for Ret Paladins. If you want to know how to maximize your DPS, follow their guide.
Of course, there is more to playing than just toping the DPS meter (well, maybe). This is especially true in the early days of Cataclysm. People (like me) who sailed through heroics clad in high end epic gear have been returned to things once past, such as having to actually worry about what the monsters are doing and to be able to bring more to the fight than just damage.
While the Retribution paladin is all about damage, he can also provide support to the party. The most obvious type of support is the Paladin buff (we now have just two: Kings and Might). Using this is simple: if there is a druid in the party, use Might. If not, use Kings. The Aura choice can be a bit more difficult. If the tank is not a paladin, then Devotion is a good choice. If the tank is a paladin, then it depends on the situation-do you need protection from shadow/fire/cold attacks, a little extra damage output, or are the casters worried about losing casting time?
While people generally turn to the mages and shaman for crowd control, Ret Paladins have Repentance which can take a mob out of the fight for quite some time. It works on most, but not all, types of monsters (see the talent). If you are playing a Ret Paladin, you can really help the party by taking a mob out of action while you kill his buddies. As always, handling CC has its own problems-such as folks breaking it with AOE effects or bad aiming. The basic tricks are to make sure that the target for CC are clearly designated and that everyone knows not to attack the CCed mobs prematurely. A good tank will pull the other mobs away so the party can tear them up with AOEs and good a DPS will let him do this.
For short term control, the Hammer of Justice can be useful-but this is very short term indeed and its main function is to interrupt abilities.
Ret Paladins also have the Rebuke talent. This interrupt has a relatively quick (10 second) cool down and hence can be used quite often in a fight. While using it will mean you’ll do less overall DPS (after all, you could have been smacking the mob rather than rebuking it) this ability can really make the healer’s job easier by preventing damage and help the party in general by preventing various unpleasant things. One key trick to rebuking is knowing which ability to interrupt-after all, you don’t want to use it on some minor ability and then see it cooling down when a mob pops out something really obnoxious. It is also important to know what abilities can be interrupted. In general, ones that you cannot interrupt will have a shield icon attached to the mobs casting bar.
Ret Paladins also get the general abilities to create, hold and draw threat such as Righteous Fury and Hand of Reckoning. In general, you do not want to use these abilities in instances/raids. After all, even though you are wearing plate, you are not a tank. However, there are some exceptions to this, such as saving the healer from a mob or grabbing a mob that you know you can (and must) quickly kill. Hand of Reckoning can also be very handy for gathering up mobs when questing.
Ret Paladins also get the various paladin hands, such as Protection (which is mainly for PvP) and Salvation. In instances and raids, these can be handy for saving the healer when the tank drops the ball or something rather bad is happening that the tank is unable to deal with. The Hand of Freedom can be a very useful hand in some cases (although it is mainly for PvP), either to free yourself or to bust the tank loose. If you PvP, you will certainly want to put a talent point into Acts of Sacrifice. This allows your Cleanse to remove movement impairing effects, but only from you.
Like all paladins, the Ret Paladin can heal and remove certain nasty effects (like poisons). While non-Holy Paladins do not excel at healing, they get all the core healing abilities, including Lay on Hands and, at the highest levels, that handy AoE healing ability, Holy Radiance.
As a general rule, you should not be wasting your time healing-the healer should be doing a vastly better job than you can. However, there are exceptions to this. Obviously, if the healer DCs or runs out of mana, then you can step in to save the day. Of course, you need to weigh whether killing the monsters faster or keeping the tank healed will be more likely to lead to a win. Another case in which healing can be a good idea is in fights that damage everyone in the party. Using Holy Radiance will probably not save the day, but it can be a nice assist to the main healer. Then there is Lay on Hands. That can, and has, made the difference between a wipe and a win. While it is tempting to save LoH for yourself, you are a paladin. That means doing things for the greater good (or not, if you just play the class for the abilities rather than for the gaming mythology of the paladin) and this most often involves doing a miracle save of the healer or tank right before that last green sliver in the health bar goes away.
Removing nasty effects via cleanse will not add to your DPS, but it can be an important role. One reason is that the healer does not have to expend mana or time that he could be using to keep the tank alive. Another reason is that there may be many bad debuffs on the party and your helping out means that they are eliminated much faster and this can make a real difference. Of course, if you are solo questing, then you generally want to get rid of any debuff you can eliminate.
Last, but far from least, is the fact that all paladins can rez dead party members. There have been a few cases in which I was the sole survivor (or at least the only survivor who could rez). Being able to rez characters can be a real time saver for the party and makes near wipes a bit less annoying by removing the corpse run.