be more flirty

This is so hard because it isn’t really me. I’ve tried smiling to a girl that I like, but then what? I’m always confused and messed up when I step up to someone with romantic intentions :) Afraid I won’t have anything interesting to say. It would be easier if I wouldn’t get carried away so easily in situations like these.
I know, flirting doesn’t always have to lead to a conversation. But just smiling and making eye contact makes me feel even more insecure.
Any hints? :D