How does a girl flirt?

I suggest just talking to him more. Lots of communication like texting and phone calls. Smile at him when you see him looking at you. A smile that says I LIKE YOU? Like smile really sweetly. Be close to him whenever you can,like sit beside him when your in a group or something. Always be close and talk to him. If he feels the same way he won't mind. He'll eventually get it. And guys like it when girls make moves too ^_^

first I think you should practice flirting with guys that your comfortable talking with but really the key to good flirting is to be yourself and be comfortable because it will come naturally when you talk to a guy.i was surprised by how much I can flirt when I'm comfortable around the guy and I don't care what he thinks.

Ok. Well don't do lines or phrases as said below. That is cringe lol, but, in saying that, notice things like if he got his hair done or he did it different, or if he is well dressed tell him! Just say 'you look good' or your new hairs nice'. I think laughing is good but not laughing at everything. Little things about you make guys go mad for you, like when your talking play with your hair a bit and holding your shoulder just above your collar bone is a big turn on. Stand like you want him, hold your arm at the joint of your elbow. Its always little things you just do naturally because you like him that is flirty. You probably are flirting already and don't know it!
xx

Don't use words lines or phrases they just sound really cheesy. Just do little things like laugh at his jokes, most of them will be stupid and he'll know that but if you laugh he'll know you like him. Don't laugh too much though it becomes weird. Keep eye contact when you're talking to him and ask him questions that he can't answer yes or no to, it means you get to know more about him and shows him your interested too :)