This thread is in the Prep School Admissions section of college confidential, so it is entirely appropriate.
@madman1 , you sound like an interesting person and I wish you luck. 1) Learn as much as you can about schools before interviewing. Make sure that you can easily express why you are applying to each school. But during the interview, try to relax - it’s a conversation, not an inquisition. 2) proofread, proofread, proofread your essays. 
And don’t forget to proofread the rest of the application.