I interviewed in early November and was accepted a few weeks ago. My words of advice for the interview: have somewhat rehearsed answers to the standard questions about healthcare, life experiences, why you want to be a doctor, etc (I say rehearsed so you have some confidence/won't stutter or freeze) but be ready to talk about them in a conversation rather than just a question-answer standard interview.
The interviewers have not read your file and really don't know anything about you so your interview is your time to show them who you are - your parents and friends know who you and would probably agree that you'll make a great doctor so you need to paint that persona for your interviewers in 30 minutes. Similarly, the student interviewer's job is to gauge whether or not he/she thinks you will fit in with the current student body, basically, whether or not they'd be friends with you. Don't take this interview lightly because I think it can really help. Be yourself and don't let yourself seem like the total cliche premed (not a very good reputation to have).
Just a last thought - I remember myself starting out giving my rehearsed answers but halfway through I realized I was staying in a box and if I did not break out of it, I would be extremely disapointed with myself afterwards. Be conservative but don't be afraid to be 100% honest. I was asked about healthcare and the theme of my response was "I don't have the answer to that question" but I managed to carry on a conversation that exposed some of my genuine opinions which led to my interviewer expressing his personal thoughts as well. I remember thinking to myself, "you know what, I AM going to talk about this," which led me to talking about how the medical community, in my opinion, is the only force that is influential enough to change American culture in terms of self responsibility starting with personal health, i.e. smoking, unnecessary obesity. Right before we moved onto a new topic, my interviewer basically said "I didn't really expect you to have the answer anyway."
These are just the thoughts that come into mind when I recall my interview. I hope some of them are useful. Don't stress over it. The interviews are the last thing so after a long day of touring and talking to people, you'll be ready to go.