First week or month is usually a little chaotic just learning all the buildings, shortcuts and the rooms where your classes are. While finding the building where your class is usually as easy as reading a map, finding your classroom once inside can be confusing if the building is old. As a freshman, most of your classes will probably be in lecture halls which are usually easy to find. But if you're in smaller classes and you're on campus early enough before classes begin, it can't hurt to familiarize yourself with where your classrooms are. Where I went to school, the English building was a literal maze where room numbers made no sense and you had split level floors. You could wander for half a hour and not find the room you were looking for.
And if you're going to a school with a big football program and you're the drinking type, a good hip flask is always handy.
Edit: Oh I forgot to mention getting some Damp Rid.