Flirting is something that gets easier if you know the person a little, even if you've only talked to them once or twice. But generally playing off what they say, or teasing them a little (this one works better and is alot easier if you know them a little, so you don't go to far) works fairly well.

I was the same as not_the_kitty when it came to attracting people, and it changed in the same way as it did for him.