Stop casting while tanking.
If you are actively tanking (and by that I mean something is hitting you over the head at that moment), do not use anything with a cast time. I've actually seen quite a few people doing this in PUGs since the dungeon finder went live, and it's a bad habit we pick up from leveling where we can get away with it. The reason this is bad is that you cannot dodge, block or parry if you're in the middle of a cast. Also, every time you get hit (well, the first two times you get hit), it makes that cast take even longer, which means you're not blocking, dodging or parrying for an even longer time period. When you're on your own doing quests, most of the things generally won't be hitting you hard enough for that to matter. However, if you're running a dungeon filled with elites, then you are better served having that avoidance than trying to cast something. You can use Exorcism to pull your next group, but don't try to cast during the fight. Don't even think of using Holy Light or Flash of Light in the middle of a pull. Leave the healing to the healers.
Ret paladins can actually CC.
Yes, you heard it here, folks. At the beginning of an expansion with no need for CC, our old Repentance was upgraded from a vaguely useful PvP talent into a vaguely useful PvE method of crowd control. It does have its downsides, but it will work in a pinch. The only things you can't use it on are elementals, beasts, mechanicals and unknowns like slimes. (Oh, and you can't use it on things that you can't CC, but that kinda goes without saying.) It's a useful ability to have on your action bar, and bringing it out to play with before the coming expansion might not be a bad idea.
Stop jumping around.
Jumping up and down is fine while tanking and is almost required for some fights, but I've seen people who never stop jumping to the left and right all throughout a dungeon while I was leveling my healer. If the thing you are attacking ends up behind you while you're jumping around, then you aren't dodging, parrying or blocking that damage. Your only real hope is that it misses. If you're sitting there in full tier 10 tanking gear and just doing dungeons for cash until the expansion hits, sure, you can soak some extra damage with no problem (and you'll probably want to for the mana return from getting healed), but I've seen this in the leveling dungeons by people who were just barely geared for the content in the first place. Your healer will hate you because he's trying to compensate for your lack of avoidance and likely a lack of good threat.
Make sure your group is ready for the pull.
This is actually aimed more at retribution than it is at protection or holy. We've gotten to a point in Wrath where we overgear the content to such a degree that people ignore if the tank and healer are actually ready and just pull without checking. I know this is because you can just burn it down with your über-1337 deeps. But, you don't have to complete the dungeon in under seven minutes. It is possible to run it at a nice leisurely pace, and in some cases, that's what the tank or healer needs. The tank might be brand new to her role, even though she's geared to the teeth thanks to the badge system, and needs time to figure out the pulls and her skill rotations. Your healer might need to swap specs and gear before people pull because he was just out running dailies and hadn't swapped everything beforehand. Slow down and enjoy the group.
Don't stand on the tank.
Don't even stand beside the tank. Bad things happen near the tank. Dragons breathe stuff at them. Big guys with swords cleave left and right with their attacks. If you get parried by the boss, that speeds up their attacks and means more damage against the tank. Stand off to the side or behind the thing you're trying to kill and let the tank have her room. Besides, you do more damage from behind, anyway, as they won't be able to parry, dodge or block you. The same goes for you healers. I've lost more healers because they wanted to stand next to me while I was tanking than I care to think about. In general, stay away from the tank, because they go places that mortal man dare not tread.
Wipes occasionally happen. Sometimes someone screwed up or sometimes the healer lags out at a key moment while you're trying to pull half the room. Sometimes, you're just dealing with inexperienced people in your party who just need some encouragement. Not everyone has been geared and playing since Wrath went live and there are brand new level 80s every day. In order to get geared up and learn what they're supposed to do, they'll need time and help to figure out what they're doing. Yelling at them to hurry up or telling them that it's "ridiculous" to still be wiping on heroic dungeons isn't going to help them learn anything so that they'll be better next time.
The Light and How to Swing It tries to help paladins cope with the dark times coming in Cataclysm. See the upcoming paladin changes the expansion will bring.
Wrath is coming to a close and the final showdown with the Lich King is here. With
Cataclysm soon heating things up, will you be ready?