Well then the thing you need to do is talk more with them, thats the only thing you can do to make it less. If you talked to some people a few times it will get easier in time and then you wont be that shy anymore too.
It's the missing that will kill you,
knowing you've missed your shot.
Talk to someone you aren't attracted to and be friendly, it'll be easier to talk to them because you're not attracted to them. Then pretend that guy you are interested is really a guy you're not interested in. The more you fear something happening, the more likely it will happen.