Any tips for constructing a rehersal room?

My band is moving to a new location, our own this time, so it would be reasonable to make it sound good. i have a few questions (too many for one post), but i will ask them later, if your tips (if you'll be so kind to give any) won't do for me. the room is about 5m long and 4m wide (so i am told, i'll check that again...) the only special thing is, that the ceiling is not paralel to the floor (wich, i think, is a good thing, am i right?) i'm mostly interested in things like: should all the speakers be in one place (almost a wall of guitar amps and stuff), or should they be seperated, what should we do with the wall oposite to the speakers... THX!