With the ease of gearing up an 80 tanking paladin, you go from being poorly geared with wonderful healers keeping you alive while you take advantage of all of the various tricks of the trade to practically soloing some of the lower-end heroics. That ability to survive anything also starts to cause your mana to run out. Pulling things at the speed you used to doesn't do enough damage for Spiritual Attunement to do any good, things are dying too fast for Blessing of Sanctuary to be of any help, and every time you hit Consecration, you can physically feel your mana pool get smaller.
While you can pray that you get a druid in your party to hit you with the occasional Innervate, you want to be more self-sufficient, which can cause you to have to change around your tanking style to keep your mana pool filled so that you can actually use your abilities. We'll also take a look at some of the bad ideas on how to handle this.
Pull more trash That's pretty much it. We're fairly warrior-like in that the more damage we take, the more mana we have. If you're fighting three guys and barely taking damage, then you might want to grab the next batch of trash as well. This will allow abilities like Blessing of Sanctuary, Spiritual Attunement and Divine Plea to work their magic. There are some places this strategy doesn't quite work, which will make you have to change other things around in order to be effective.
Judgement of Wisdom One of the easiest ways of making sure you have more mana available is to judge wisdom instead of light. Yeah, no-brainer, but people often get into the habit of running around judging light, as it makes us more self-sufficient when questing.
Seal of Command It's an ability, but it's a talent. I decided to put it here. This is actually a nice way to get free AoE threat if you're talented into it. The current Seal of Command essentially cleaves (yeah, I know it technically chains, but bear with me), which means each time you swing your weapon, you hit two other targets for some holy damage threat. There's also a glyph for the ability that helps out, but we'll talk about it later.
Blessing of Sanctuary If you're above level 30, you should be using this as your go-to blessing. It boosts both your stamina and strength by 10% now, so there is little reason to choose Blessing of Kings over Sanctuary. You get mana from the dodges, blocks and parries you make and if you're overgeared, there should be plenty of them. The only problem is if you're killing things fast enough, they don't really have an opportunity to hit you. When in doubt, pull more trash.
Divine Plea Once you get this at level 71 and the prot talent Guarded by the Light (which you should already have, but more on that below), you should attempt to keep it up at all times. The problem is that some instances (*cough* Violet Hold *cough*) force trash to spawn so slowly that Divine Plea will fall off before the next batch of trash appears. However, keeping this active also falls into our "pull more trash" strategy.
Divine Sacrifice Yet another talented ability. While you could use this technique with Hand of Sacrifice, it's much more helpful this way. If you're in a fight where people are taking a decent amount (but not huge amount) of AoE damage, just pop on Divine Sacrifice and redirect it your way so that you take enough damage that Spiritual Attunement can make use of the heals. It's not an every-pull solution, but if you're in need of mana and people are taking damage, then go for it.
Retribution Aura If you're barely taking damage anyway, then might as well swap out of Devotion Aura and get a little more threat against things hitting you.
Spiritual Attunement Avoid two points; just put one point into it and move on. Being overgeared means you're not taking enough damage for it to matter, anyway. You usually want to leave a point in it for those fights where you are taking good damage. Plus, you can put that extra point you saved into Seal of Command over in the ret tree.
Guarded by the Light This is a wonderful ability when combined with Divine Plea. As long as you hit something with your weapon every 15 seconds, you'll keep Divine Plea up and running.
Glyph of Seal of Command Probably your best bet for mana conservation. Judging costs 5% of your base mana. This glyph returns 8% base mana. That means every time you judge, you gain 3% of your base mana. That's around 100ish mana gain as well as your judgement ending up being free. Plus, you'll be doing more AoE threat with Seal of Command than with Seal of Vengeance/Corruption, when dealing with larger groups that die quickly. If you need the expertise from your Glyph of Seal of Vengeance for bosses, you could keep both or just carry a stack of both glyphs to swap out as you need them.
Minor Glyph of Blessing of Kings This is only really helpful at the beginning of an instance where you're buffing everyone. However, it does save a decent amount of mana in that situation, especially with the size of our mana pool.
Minor Glyph of Lay on Hands This is an old ret trick, to use Lay on Hands as a way to get a little boost of mana. Also, it gives you more access to the ability in case someone accidentally pulls aggro and you can save the healer or yourself.
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?