I need some advice.

I don't have the best luck with girls. I've asked a few girls out before. The first 2 just wanted to be friends, I think I may hvae even scared the 2nd one off.

The 3rd girl I asked ended up having a boyfriend.

I just want to know. How can I tell if a girl is interested and not just being nice?

Also, what's the best way to approach a girl? I've heard that guys should try to be friends first. Does this mean just getting to know them better?