1. Be around people. It works best if you can spend a repeated chunk of time over and over again (work, school, clubs)
2. Be friendly, but not a needy weirdo
3. Pick out someone cool
4. Say "Hey, we should hang out some time" then change the subject. You will avoid being directly rejected, but let them know you're interested in being friends.
5. Listen to what they are interested in and speak up when you have something in common.
6. Hopefully they will ask *you* to do something.
I've been gone for a while and had excellent success with this technique.