Productivity at its finest!
WORK ON YOUR SCHOOL WORK (DUH!)
I know, I know. This is the most obvious choice. This is the #1 thing to do when you have free time on campus. Work on that assignment that's due, start on that project that's due a 2 weeks from now and study for your classes! This will benefit you in the long run.
PLAN YOUR SCHEDULE
Use your free time to plan out your assignments! Whether you have your own personal planner or even on a blank sheet of paper, it is important to plan when you'll do your tasks so that you won't miss anything.
JOIN STUDENT ORGANIZATIONS
This is the perfect way to engage in school activities and make new friends. Plus, student organizations come in handy when writing your resume.
TALK TO YOUR PROFESSORS/ADVISORS
Take advantage of your professors office hours. It is a good way to stay on top of class, make sure you're not missing anything or clear up any troubles you might be having in class. It also helps you make a connection with your professors.
ON CAMPUS JOB
A little extra money never hurts! Get on on campus job or a work study job.