Most off campus housing options provide roommate matching programs, where you will fill out a questionnaire describing your personal habits for things like quiet hours, studying, partying, cleanliness, and values. You'll then be matched with students who answered the questions similarly. You also may have met friends in on-campus housing, classes, or on campus organizations who you want to live with, in which case you will want to make sure that you list preferred roommates on your housing application.