Talk about your problems and issues. Listen to what your roommate has to say and explain your side of the situation to your roommate. If you can get your problems out in the open, you can deal with them more effectively.
Devise a set of room rules. Base these rules on compromise. Try to be fair with the rules so you and your roommate can both feel good about the rules. For some roommates, writing a room rules contract can also help. Be sure that you and roommate both have a copy of this contract. You may also want to post a copy on a wall in your room.
Avoid each other if you can. If you and your roommate just can't get along, limit the time that you see each other. If your roommate plans to study in your room, maybe you can go to the library to study. You may even want to stay with a friend for a few days if you really need a break from your roommate.
Get help. If you live on the college campus, look to your resident advisor, the office of residence life or counseling for help in dealing with your college roommate. Your college may also offer mediation services to help you and your roommate. Don't be afraid to ask for help or advice if you need it.
Move out if all else fails. Some people just can't live together even if they have tried everything to make it work. In these cases, see if you can move to an open dorm room on campus or if you can move in with a friend. Alternatively, your roommate may choose to move out of your dorm room.