Since you are going OOM a lot Seal of Wisdom is NOT the way to go, you want to get Glyph of Devine Plea and keep up Devine Plea (the glyph resets the ability each time you attack). The seal you want to use is Seal of Corruption and make sure you have up Righteous Fury, you are using the correct buff (BoS). For your rotation you should be doing Conc, Holy Shield, Holy Wrath, and any other attacks that do Holy Damage. Holy Shield and Conc are your main threat keepers and they are a must to keep up. Paladins are the easiest threat keepers when you are handling adds, Holy Shield and Conc will help you out along with Avengers Shield. Do not spam Hand of Reckoning on a boss because if you happen to lose threat that skill will be needed and it has a 6 sec CD, that might seem like a little but that is a long time when you have, for example, KT running around like a mad man, which he is O_O".
That is pretty much all I can think of, Def cap is 540, if you are at the cap and getting better gear start gemming stamina.
I'm on a boat, doing flips n' $&!%