Flirting is a form of communication that shows appreciation, attraction, and/or interest. It is of the moment and should be offered WITHOUT long-term goals! When you flirt, have only flirting in mind. Don't think about what it could turn into, because you should flirt for the enjoyment of putting your positive feelings out there for someone to enjoy. Flirting should be genuine and sincere, not flighty and irresponsible. The ability to flirt is the ability to take control of yourself and have an impact on the world! I can't stress enough that flirting is to make someone else feel good about themselves. When properly achieved, it is healthy, enjoyable, and refreshing for both people involved.
Now I suppose the greatest question is "How do I flirt?!?" Good, because that's my next answer! Two BIG words: EYE CONTACT! I cannot possibly cover this one enough. It is the absolute most important part of flirting! Make eye contact with your target. Glance away on occasion - this is very important because otherwise you'll appear to be staring. Once you've established eye contact, smile. REALLY smile - not the little grin you offer your teacher when you hand in a test - offer a heartfelt smile. A smile is the primary form of nonverbal flirting!
Other forms of nonverbal flirting
The Wink 
- There is only one rule for winking i.e. Wink Only Once. This is very important! If you wink more than once, you're not flirting, you're getting something out of your eye.

Body Positioning - Make yourself look friendly. Don't stand straight and cross your arms. That says "GO AWAY!". Lean a bit and splay your arms and legs about as if to say "COME ON OVER!"
Twirling Objects - From drinking straws to ink pens and peanuts, twirling or fiddling shows you're a little nervous - it's important to make your target feel more comfortable and less like a target.
The Touch - Feathery touches and minimal grooming gestures (such as flicking a piece of dust off of a jacket) are a way to show interest. Use good judgment here, as you don't want to invade your target's "space".
Mimic body language - Don't be a parrot, but if your target shifts to the left leg, you shift the same direction (your right). It's another subconscious way to set your target at ease.
*
lecture materials prepared by Master-_-*