How to get more confident around girls?

Just wondering how old you are if they are saying "we don't have cooties"? I'm assuming middle school/early high school? I used to be super shy around guys. Especially if I liked them, I couldn't talk to them-definitly helped them to know that, right? =P By talking to guys more in casual situations like work, class, intramurals, etc. I would be more confident for when I would be in a different social situation. I am an introvert, and I want to try and be more social in general, so sometime I think of things to talk about ahead of time in case conversation goes flat. Hope that helps!