I hope no one is offended by this, but honestly, boys do not understand flirting! I've even had guys ask me advice about girls and be like "I suck at interpreting flirting." And sometimes, it leads to awkward situations.
Sometimes a girl will flirt with a guy. She can be practically throwing herself at the guy, and he'll be like "Der... Does she like me?" Which is why many of my guy friends constantly ask me for girl advice, because even if a girl is flirting heavily, they still aren't sure. A girl will laugh, touch his arm for no reason, and compliment him. THAT'S FLIRTING.
Other times a girl won't be flirting with a guy and yet for some reason he thinks she is. This has happened to me SO MANY TIMES. Just cause I overuse emoticons when texting and laugh at your stupid jokes doesn't mean I like you. All of my guy friends have asked me at one time or another if I liked them. Even though I don't!
Or a guy will be flirting with a girl, but in a really dumb way. You have to make your flirting clear, with a tint of ambiguity. Saying weird things and the girl not reacting doesn't mean she doesn't like you.
Tips for girls: Try not to be super ambiguous when flirting if the guy doesn't appear to be getting that you like him. And don't throw yourself at him! You'll probably just scare him away. And please realize that this is the twenty-first century. It is perfectly ok for you to ask a guy out. Just cause a guy doesn't ask you out doesn't mean he doesn't like you, some guys are just shy! So don't be afraid to either initiate a conversation or ask him out.
Tips for guys: If you're not sure whether or not a girl is flirting, you can always ask someone. A girl friend is perfect for these situations. My guy friends are constantly asking me "Is she flirting?" Also, don't interpret every little thing as flirting. She smiles a lot? Maybe she's just friendly. And don't be super scared of rejection and therefore not ask her out. Be confident, smile, and just do it. What's the worst that can happen? What's the best that can happen?
Overall, flirting has become really weird. Everyone thinks that people they don't like like them, and that people they do like don't like them. If you like someone, flirt for awhile, and if that doesn't work, just say those six magic words:
"Will you go out with me?"
Avoids a whole lot of confusion.