This greatly differs depending on the gender, and no, I am not going to encourage homosexual or lesbian flirting. This is strictly heterosexual, as God intended. Generally, giving good wide genuine smiles is a great way to break the ice. Laughing is a great way too, but you can laugh too much. The difference between a perv stare and a intriguing one is the short bursts of eye contact, which comes, stays a bit, and leaves, with the intent of having you thinking of them until you have to talk to them, or until they make the move, but the guy should make initiative. In bars, sitting close and offering drinks is obvious, as is the toying with the hair, especially for longer haired guys and most girls. I would never go to a bar (for any reason), but you should already know at least how to pick up on those kinds of things. Also, if they are leaning toward you, or if the girl has crossed the opposite leg over the one next to you and her foot is pointing to you, you got a really great chance. Another obvious one is if they are with friends and trying to catch your eye while smiling or laughing, you should realize that they could be as into you as they are into their friends.

flirting is an art - there are actually classes you can take - ppl feel good when you are interested in what they have to say and smile, smile , smile!