Did a guy friend try to flirt with you and you didn't know what to do or what to say? Next time it happens, you'll be ready.

[edit] Steps

Learn to take a compliment. For example, you and your friends are hanging out together (guys are included) and one of the guys starts staring at you, or even tries to come and talk with you...OR (if you're lucky enough) tells you that you look cute in "that outfit". You shouldn't just look stunned or surprised; just act naturally and say thanks with a cute nice smile.
Flirt back. How? Well, if he comments on your outfit saying that it makes you look gorgeous, you can also tell him he looks way "handsome" in that "shirt".
Avoid changing your voice tone, or acting differently in general. Just be yourself.
Don't rush things. If by the end of this meeting he asks you out or even asks for your number, don't answer right away. Give him some time to chase you.

[edit] Tips

Good flirting requires good breath and no body odor. Always make sure you have mints in your purse...and shower regularly.
Always take good care of your hands. Hands, trust me, says a lot about its person. Have your nails done, and get your hands always moisturized.
Don't wear too much make-up. It may make you look slutty. Just use some blush, light eye shadow and a lipgloss that suits your skin.
Try to be a good conversation-initiator..guys like that about girls. That implies your good command of dealing with people, and that you're open-minded and outgoing.
Develop a good vocabulary. Use words that shows his masculinity, like handsome.

Don't fall for the guy too fast; he could just be a flirt.
Don't stare too much at him, he might freak out. Just keep it light and simple, every now and then throw him a look and then look away quickly.Maybe twist your hair while your at it.