How to know when a guy is flirting with youIf he is asking a lot of questions about you, your life and what you do. This is actually bad form on the part of guys, as it can lead a woman to feeling like she's being interrogated! But most guys actually aren't very good at flirting and asking questions and hoping to stumble across an coincidental common interest or connection is as advanced as most guys get.
If a guy is telling stories about himself, he might be flirting, or he might just be a blowhard or braggart. It can be hard to tell, but if his story is relevant to a story you just told, or is a follow up to a question you asked, there's a good chance he's flirting.
If a guy compliments you, 9999 times out of 10000 he's flirting. If a guy asks "pre closing" questions like "Wow, it's great that we both like X, we should hang out and talk about that sometime" he's absolutely flirting and is all but asking you out.
If a guy is doing two or more of these things, he's definitely interested.
If a guy makes lots of eye contact while you're talking, laughs at your jokes (even when they aren't very funny) and /or smiles a lot, he's probably interested and is actually flirting.
If a guy teases you, in a joking fashion, he's flirting, but be wary... some guys who have studied the material from the "PUA" scene try to do something called "negging" and some of them aren't very good at it and accidentally say things that make them look like total assholes. Of course, some guys simply are assholes and it can be hard to tell the difference. Net-net, if a guy says something teasing towards you and you find yourself laughing along with him, or engaging in friendly back and forth banter, then it's flirting. If a guy says something teasing and you are insulted, he might have been trying to "flirt" but he's clueless. Honestly, from a woman's perspective it's probably better to just disengage at that point, unless you find yourself really interested in the guy for some reason.