There isn't really much you can prep for with the new content. The guides that are out there are few and not necessarily reliable. With so much content to digest, the major guide-makers aren't able to produce guides in mere days like they can with regular patches.

This is the time to enjoy not needing to know everything in advance. When I enter I'll usually type a quick greeting of "Hello! This is my first time running this dungeon so I'm going to keep pulls restricted to 1 or 2 packs at a time" and go from there. When we get to bosses I will stand inside the ring and wait for just a few seconds to see if anyone types things they want me to know for the fight. So far no one has and I've gone 1/1 on every boss encounter. I'm currently through the level 55 dungeon and I have had no problems with these methods yet. Only the rarest of jackasses gives people a hard time about not knowing everything when it's a full blown expansion that's under a week old.