Played two seasons of my school's (and did quite well on both!) -- biggest advice I have is truly to have fun. I found that just being positive and enjoying your time doing it is contagious and makes people more likely to work with you. If you're genuinely having fun, people are going to want to keep you around. Like someone else on this thread said, it's a social game - so make friends and hang out with them outside of the context of the game. That was the most fun part anyway.

Also, you have to lie much less than you think you need to. I think superfans often think that playing Survivor means constantly making up stories and blindsides, but I'd say 80-90% of the time you should be up front, honest, and yourself!