Not sure what degree your going for, but I just graduated from college with an EE degree, and I'll be starting grad school next week. Here's my advice:
-Have fun and enjoy classes (Go to them!) You'll learn a lot from your professors and other students even though you may initially feel like they are a waste of time. Also in smaller classes the professor notices.
-Also on classes, it's important to make a good grade, but it is also important what knowledge you take away. There are quite a few fundamental classes that I got an A in, but I retained very little that I am regretting now.
-If you are not being challenged in a class, esp. programming. Talk to the professor, and they will probably find a way to make it more exciting/interesting.
-Like you said, meet as many people as you can. This is esp. true the first semester. Everyone is excited about meeting new people.
-I would also recommend finding something outside of you subject area to balance your life out. For two years I was a cheerleading at my school. Met a lot of cool people/girls.
-Depending on what your major is, you may want to talk to a professor you like and see if you can get a job with them. This will cut down on your personally time for hacking and relaxing but makes up for it with great experience and recommendation letters.
-Once again, if you are doing C.S. or engineering look into REU's, Research Experience for Undergrads. I spend a summer at USC in their robotics lab for an REU, with housing, meals and a stipend paid for by the REU. Awesome time and I got a lot of letter of recommendations.
-Finally, be safe and have fun!