College is sooooo fun! DH and I are seriously thinking about going back to college when we retire in about 20 years.
My advice:
Try to eat healthy and get regular sleep.
Go to your classes. I skipped waaaay too many 8 a.m. Physics classes my first semester and it made my life much more difficult. Would have been totally better if I had gone to bed at a decent time and gone to class.
Introduce yourself (exchange phone numbers, etc.) to at least one person in each class in the first few weeks. That way, you'll have someone you could get a copy of notes from if you get sick and/or have a study partner.
Try new things. There are so many different opportunities at college -- if you hear about something that sounds like fun, try it! I took a weekend rock climbing course through the rec center, rented camping gear from the rec center, took flying lessons at the local airport, took swing dance lessons, played soccer through the rec center -- basically had a blast.
Oh, if you party (and you probably will at some point), go with a party buddy. Go to a party with a good friend who will make sure you "go together, leave together", avoid leaving your drink unattended (could get spiked), and don't give out your last name or room number to members of the opposite sex you've just met. Also, know your limits and don't drink excessively. (Not to freak you out, but there's a pretty high incidence of date rape at colleges.)
Enjoy yourself! College is so much fun!