If I'm dpsing, I try to check the dungeon journal before my first-ever-on-this-boss pull, at least to see the loot table, and usually if it's going to be single or multi target, and sometimes to see how much movement there is and what the fire will be. When I'm tanking, I check out the Icy Veins guides and another LFR-specific quick tanking guide before I even queue. In any case, it's not until the pull that I really understand the fight.