Guys - How do I flirt with a guy I like without seeming trashy - ten points?

Long story short - a guy I like, don't know much about him. I think he might like me too ( stares, smiles ) . How can I subtly send out a signal that I like him without being too over the top? I'm pretty shy, so I'm not the aggressive type...I'm asking about body language, signals, etc. I want HIM to know he can make a first move. What does a girl do that makes you think she likes you? What is an attractive way to get you excited? Thanks!