The most successful roommates are those who actively work to make their living environment enjoyable. It's not easy to live with someone - especially someone you don't know well; prepare yourself to be accepting and respectful of others and bring with you an open mind and enthusiasm to interact with all types of people.
If you're struggling with living with someone who is different than you, focus on what you have in common. What hobbies do you both enjoy? What TV shows do you both like? Once you've got that down, practice your communication skills in other areas. Start the year by setting ground rules for your living space. Determine what items are okay to borrow, what time you'd like to go to bed/wake up, and figure out if your roommate is okay with guests spending the night. Establish room-rules early in the semester and revisit them throughout the year.
This will help you and your roommate avoid conflict, but know that it could still arise. If you do find yourself in a conflict, be sure to address the issues quickly and courteously so negative feelings won't fester. Talk to your roommate openly and honestly before talking to friends and floor-mates. Be ready to listen and be prepared to compromise. If you're having difficulty coming up with a good resolution, ask for help from a neutral party like your Residential Life Student Staff Member.