Tip 1: To thine own self be true. Sometimes the housing office gives incoming freshmen questionnaires about their living and studying habits in order to help match them with compatible roommates. Fill these out honestly! If you're a messy person who likes listening to music at all hours, don't be ashamed to admit it. Of course, roommate assignments often bear no relation to the completed questionnaires, but at least give the housing computers a chance to pair you with somebody suitable.
Tip 2: Speak up. Get to know your roommate. Even if you're not great friends, you'll be able to get along better if you understand each other. Discuss what you expect from each other. Don't be afraid to tell your roommate if his/her actions bother you. Let each other know when important events (tests, papers, competitions, etc.) are coming up.
Tip 3: Silence is golden. Yeah, we just told you that you shouldn't be afraid to discuss things with your roommate, but you'll probably be better off if you don't tell your roommate about all of her little annoying habits. Think long term. You're going to have to live with your roommate for an entire school year, so don't nit-pick or judge her on how she acts the first week of school. It takes people a while to adjust to college life and living with a stranger, so give your roommate the benefit of the doubt before criticizing his/her actions.
Tip 4: Plan ahead. Decide how you're going to handle financial obligations (e.g. phone bill, groceries) ahead of time so there won't be any misunderstandings when it's time to pay. You should also discuss whether borrowing or using each other's property (e.g. stereo, clothes, toiletries, etc.) is cool. Establishing boundaries is fine as long as both roommates are aware of them.
Tip 5: Establish company policy. Decide whether it's acceptable to bring a boyfriend/girlfriend back to the room. Figure out how the roommate entertaining a guest will let the other roommate know when he has company.
Tip 6: Do unto others… Whether you like your roommate or not, treat him with the consideration that you'd like to be treated with. Set an example and with any luck your roommate will catch on.
Tip 7: Give a little. You don't have to subvert your personality to get along with another person, but be prepared to compromise. If you're naturally a slob, you should learn to be neat to the extent that you don't encroach on your roommate's space. If you're a neat freak, remember that your roommate may not be as offended by mess as you are.
Tip 8: Don't stress. Most roommates naturally figure out how to get along even if they don't become best friends. In the unlikely event that you find yourself in a living situation that's unbearable, you'll probably be able to switch to another room.