How a Pally plays really changes as you level. Even within the same spec, so it is kind of hard to give a clear cut answer.
1)As a ret leveling you will want to get a slow 3.6 2h. Start by judging with Judgement of the Crusader, then Seal of Command. Judge command when it comes up. When you get high enough for Crusader strike you will throw that into the mix.
2)Ret Aura till you get Sanc aura. Someone did the theorycraft once, armor vs minor dps boost and dps boost won for grinding purposes.
3)Somewhere into the 20's you can use BoMight, but eventually you will start to notice that BoWisdom is much more effective for grinding and will reduce your downtime making it much more worthwhile than Might.
4)Stack Str (for AP) and Agi (for crit). Don't neglect Int or Stam or you will feel it, you will have more downtime than you want if you neglect those two.
Remember you have a bunch of neat little tricks that can save the day in a number of situations, Judgement of Justice on runners is a big thing, etc. At lvl 35-40 Prot becomes very viable for leveling. Don't look at holy till you are gearing up for end game, I did it at lvl 67 and it suuuuuuuuucked.
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Bode - 100 Holy Paladin - Lightbringer