I would recommend preparing by relaxing, watching TV, hanging out with friends and family and avoiding anything that looks like school.
The amount of work you'll be doing just to keep up (not to mention trying to excel or beat out other students) will be far more than you've ever done, and I promise you won't understand it until you're there. Studying now will add minimal understanding of the new material, and you'll wind up just being bummed out and tired faster.
You'll have plenty of time to be overwhelmed with new info later; just chill, friend.