I can only say this because I've tanked a few things as a protection paladin (not raids, but I've tanked enough instances to know the most basic of basics of paladin tanking) and then if you look at my sig you'll see that I've recently created a warrior which is my next project to level up, and honestly if you want to get a real feel for what it feels like being a tank, go warrior. Paladin tanking, to me anyway, feels more like a hyper-grinding; just the mobs happen to be in an instance instead of out in the world. You really don't have to do anything special about tanking that you wouldn't do while AoE grinding, but warrior tanking as I'm beginning to find out, is a lot harder than it looks. I think that by leveling a warrior, I'll get a better feel for how the MT is having to play in a raid and maybe I can anticipate what he will do a bit.