the best way to prepare yourself is as KPmum said.
YOU ARE ALWAYS WRONG. regardless of what you think you know, you know nothing. be prepared to be screamed at for absolutely no reason whatsoever. it happens. also, know that you will be put on your face and made to do push ups over the most trivial of things.
realize that the upperclassmen don't actually hate you, regardless of what they might make you think. it's all just a big game. play along.
remember that they don't hate you, it's nothing personal, and that every one of us has gone before you and had to do the same thing and it makes it easier.