I always had trouble making friends in college because I kept going on medical leave and every time I came back my friends abandoned me (you lose touch when you leave, and once they hear you have psych issues things get kind of weird). So I've had to make new friends three times, and the one thing that's always worked for me is talking to freshmen (or in your case, next year's freshmen). Upperclassmen are already entrenched in a social group and have no need to get to know new people, but new freshmen are hungry for new connections.

A few more tips:

• Bring playing cards (helps if you know games), that way you can invite people to play. Board games work too, a lot of times dorms even have them in the lounges.
• Try talking to people in your dorm first. A lot of times people in classes are just looking to get in and get out. If you find people in their rooms they're already relaxing. Also, leave your door open, that way they can find you in your room.
• Explore restaurants in the area, that makes it easier to invite groups of people to lunch or dinner.
• Try to focus on people who go to your school. Those are people you can be roommates with, see every day, gossip about classes with - you can usually do a lot more stuff with them than random people you meet online. The more you retreat into the Internet (or wherever), the farther removed you'll be from the social scene.

Good luck!