OT : Go over your resume to the point that you can recite it without looking at it. Go over any sort of speech or phrases you may use so you can roll them off without saying "Uhhhhmm", because you'll find that you use the word a lot without knowing it!
Assuming that you are male, give a firm handshake.
It's a little late, but when you are 1st starting out, it never hurts to apply for a shit job that you don't intend on taking just for the interview experience. After you do enough of these it'll take the nerve off when it really counts!