Watch others around you. I used to be a shy, reserved kid that mostly hung around with other geeks and introverts. Later, around the Eleventh Grade, I started spending a lot of time with my hypersocial older brother and his 'cool clique'. I noticed that while his circle did have several advantages - witty, generally good looks, arrogant confidence - the key to their success was resilience. Sure they struck out a fair bit as well. But they never gave up. I tried to emulate that, then later I actually became that guy (i.e. no longer pretending). By the time I hit college, I was actually one of the popular kids. The connector that knew everyone. Sure, later I became a recluse after I got jaded with the life but that's a whole other story.
OP: any generally decent people at work/school? A little generic chit-chat around the water cooler, just enough for them to recognize you. If you are pleasant and non-creepy enough, it should only take a few days before someone asks you to join them for lunch/beer/whatever.
Most shy people generally see some kind of major flaw/defect in them. For me, it was massive overbite that I had corrected in the Tenth Grade. I'm pretty sure the overbite was the reason I felt so self-conscious all the time. Do you have anything that bothers you (about yourself)?