<p>Interviews can either be evaluative where the results are used in admissions, or non-evaluative where the interview is offered by the college just to answer any of your questions. They can either be given by adcoms or by volunteer alumni in your area.</p>
<p>If the interview is evaluative, it won't count for much, but you could hurt yourself by coming across as arrogant jerk or some other undesirable type. </p>
<p>Probably the most important thing to remember is just to show up. Colleges like you to show interest in the college, and if an interview is offered, it is pretty much required that you agree to it. Colleges who offer interviews have volunteer alumni across the country and they will hook you up with one of those. (If they can't, it won't be held against you.) If you live with about 200 miles of the campus, you should visit the campus. Make sure they track all of your "interest".</p>