DO say no to friends once in a while. There's a time for schoolwork and time for fun.
DO keep an open mind about your roommate. You don't have to be best friends, but you need to have respect for each other.
DON'T leave your laundry in the washer/dryer for several hours. Respect other people's possessions and ideas.
DON'T leave a mess in the kitchen.
DO become involved on campus with clubs and activities.