Have 3-5 questions ready for your interviewer. And not just your standard fare such as "did you like going to X school?" Of course they liked it. . . they loved it or else why would then take an hour out of their day to interview you? Come up with 3-5 well thought out, well research questions that actually matter to you. If you have a particular interest, or a major you want to pursue or a club or program that you're dedicated to, do some research and ask a question about it. Remember, you're interviewing the school as much as they're interviewing you. You'll be there for 4 years so it has to be the right fit! This is your one chance to get a more personal perspective on the school so utilize it well!