How do you flirt with someone?

I work in a coffee shop, and one time my best friend came in with one of her co-workers. This guy is so hot, and he has like the exact personality that I've been dreaming of.She's the only person I've ever come out of the closet to. I'm a virgin and never even kissed before. And she claims that he's gay and has never been anyone before either. (She is very nosy by nature and stalked him enough to find this out.) That makes me feel better, but I still don't know what to say to him.He comes in like twice a week now, and when I'm serving him, he asks me friendly questions like, "Busy today?" and I just give him good answers like I would to any other customer. I have no idea how to flirt or even if he's into me.My friend said she told him I had a crush on him, and he didn't believe her but seemed pleased at the idea. I get really embarrassed when he's in now, and I don't know if I should say something or not. She says I should just say something like, "You're delicious," but I don't know how to pull something like that off without being creepy.