Women don't hit on guys the way guys hit on girls. So, let's say you like a girl, but you’re not really into her. The way you talk to her in that situation is about as forward as most girls will ever get with any guy, no matter how much she likes him.
We have sexism to thank for that. If girls weren't constantly being called sluts for displaying any amount of sexuality with a guy, then they'd feel more comfortable with it.
If you like a girl, ask her out yourself. That's the only way it really can be.