Talk to your roommate and her friends. Get to know the other people in your dorm or apartment building. Helping people move in allows you to meet new people in your building.
Talk to other students in your classes. Classes that you picked yourself, such as an art class, will have students who share your interests. Find a "study buddy" with whom to exchange phone numbers in case one of you is unable to attend class.
Join a study group or a club. On or off campus, there are plenty of activities taking place where you can meet new friends.
Volunteer in your free time. Chat with other volunteers and you can expand your group of friends to include people who may not attend your college.
Sit with a group or a person at lunch whom you've never met. If you have to eat alone, find another person sitting alone and ask if you can join him. If you're eating with friends, find a single person or a group and join them.
Attend school functions such as dances, games or concerts. Spend time at the library or gym.