First off, good luck with your interview!
Fortunately, my interview with Dubuque was my second interview so I had a little practice beforehand!
My biggest advice is to talk with the other applicants. Everyone is nervous, and making a friend or two can do so much for your nerves.
Also, know your application and have more than one patient experience to draw from. My interviewer asked me to tell her about a patient experience that has stuck with me. I wrote about a few patient experiences in my essay, but made sure to have a few others to talk about.
Lastly, be yourself and just breathe! If you don't know how to answer a question, take a drink of water to buy some time. Remember the adcom wants to learn about you, so take that opportunity to sell yourself.
Anyway, I've droned on a bit long. Good luck!