Talk to the foreign students in your classes. You can learn a lot about the world that way.
Once your schedule’s sorted, why not join a committee or club? I was on my uni’s music and entertainment committee for two years. I had a lot of fun and got to a lot of shows for free!
IF you’re going to join a fraternity/sorority, please remember that doesn’t make you better than anyone else.
Get to know your Teaching Assistants and get on their good side. Unless it’s a small class, your professors are going to have a lot of students wanting their attention. Try to get that, of course, but in larger classes with discussion sections, your TA will be the one making the major decisions about your grade.
If you’re going to live in a dorm, get on your Resident Assistant’s good side, too.
Find out who your department advisor is once you pick your major and cultivate a relationship. I got a first notice of an internship on a big TV show just by being in her office while she was opening her mail.
There’s a lot of relationships you’re going to be making! Good luck and enjoy yourself!