If i'm new to a dungeon or a raid or anything i usually just say 'hey i'm new, is there anything i should know about this dungeon?' and 97% of the time people will tell me the mechanics of stuff when we reach it,
and vice versa, if someone is new and doesn't know the instance, i usually ask who, and explain parts of the dungeon as we reach them, it works out well,
the 3% are the anti-social ones or the ones who don't speak english, but i end up working out the mechanics on the fly, or ask in my FC chat while on route to boss.