How to impress in a panel interview

I have a panel interview coming up for a new grad residency at Northern Westchester Hospital. I have been preparing for behavioral/situational questions. I am feeling quite nervous! The last interviews I have been on were really easy and I do not think that this is going to be an easy interview! Any tips on what I might expect? I know that I would be a great candidate for the job, now how do I relax enough to sell myself in the interview?? Also, what do people typically say during the "Tell us about yourself" question? I usually talk about how I like working with people and my past experience working with developmentally disabled students and why I went into nursing.