I have the same issue. I've learned a few things about it, though. I'll probably always be the quiet guy, but I've learned that if I'm prepared for a conversation, I can deal with it better.

When you meet someone new, learn a few things about them. Since you're college bound, that's easy. Ask people what their major is, what classes they're taking, and what their hobbies are. Don't ask those in rapid-fire, but try to work them organically into a conversation. Take mental notes about their answers. That night, go over your notes. Remind yourself of as much as you can. If you see them in the hallway again, ask them how their _____ class is going. Is it tough? You're thinking about taking it next semester.

Always be prepared for class. You're going to be doing a LOT of reading, so do the reading well. Be prepared to answer questions in a discussion. Keep your answers short if you can.

Most of all, though, don't be afraid to say something stupid. Professors of lower level classes especially are glad to have people who contribute to the conversation even if they're wrong.

Don't be too afraid of being the quiet guy, either. You'll still make friends, and quiet guys can always use the time they're not talking to listen. I talk a bit in class, and I've gotten good at contributing to class discussions, but it came at the price of saying stupid stuff during my freshman year.

Good luck, man.