Just be yourself, enjoy yourself. These things can be fun if you can get over your nervousness. Just treat it like a conversation. The more questions you ask and the more you talk, the less questions they can ask you. Remember, you get freebies, and get to talk to awesome people, spend the night in a 4 star hotel, and free meals! Doesn't get better than that : ) I enjoyed my conversations with the interviewers and other candidates.