How do I become less quiet and shy?

I'm sick of ALWAYS being avoided by people cos im the quiet one, i mean i hav friends its just even they think I'm a bit quiet and I don't know what to do. I'm just quiet because I'm afraid if I say something wrong or whatever and then everyone will be talking about me and arhhhhhhh i really don't want that. I wanna revamp my personality over the summer, how?