You can say I am, or at least was, a shy person.
I don't think you can change that about yourself, at least not in a short time. I have come to understand that you never really lose, you "shyness" but you just become accustomed to the situation.
I was very very shy at a younger age and lucky me, the first job I landed was a door to door sales person. What a contrast. I hated the job for the first week, but after a little while, you become used to it, you are still nervous, but it doesn't feel as bad.
My suggestion is to change your view. My problem is that I think everyone is looking at me or talking about me or whatever. I think this is a common problem. The truth is, people just don't care, now if you are holding a big camera, they might look, but in an envious way, they think that you are a pro. Try this one time, sit at a busy coffee shop and watch people, they don't pay attention to anything, people are always thinking about the next thing they want to do.
RFM also makes a great point, talk to people, just walk up and break the ice. I have made it a habit of of asking people question in public or commenting, like "nice car" or asking them about a shirt they are wearing that I like. You slowly start to feel it is routine. Luckily for guys like us we live in Canada, and well, people are pretty damn relaxed. Nothing against Americans, but even I don't feel talking to people, especially big cities.
It's really a head on approach, you will be so surprised that people are willing to respond so nicely, the thing is to not forget the majority of people are the same as you and I. They aren't all crazy judgemental psychos, well as long as you don't try to talk to a woman from Toronto, especially hot ones. hahahaha