One thing I've found is that
flirting seems to work better when you're not actually
trying to get
anything from the person you're flirting with, but just doing it because
flirting is fun. It's the
confidence issue at work here - when you're with a
friend who you're not thinking about getting
anywhere with, you're not going to get
uncomfortable or
doubt yourself, you'll just go ahead and do it. I've had a few
relationships that were
unplanned due to flirting with someone who was just a
friend. I've had much worse
luck when I was
consciously trying to get them to
like me.
So stop trying so hard. It's not a race or a competition where you need to get them as fast as possible. Try and become friends first. Not only will you be more comfortable around them and more willing to flirt a bit, but you get to learn what they're like, and find out if you really even WANT to be with them.