Okay. A friend of mine uses these two strategies to attract girls and flirt. It sounds kinda stupid but it's worked for us several times and works on the same principles as/are basically similar to other suggestions here.
The first is to keep teasing the girl about already being attracted to you/falling in love with you/wanting you/whatever your goal is.
"Hmm, you're replying to my texts so fast, you're not falling in love with me, are you?"
"Did you just sigh when you said my name? you're in love with me, aren't you?"
"There, I was on time. Will that make you fall in love with me now? Come on, what else do have to do? Please love me now!"
Of course, you have to be cool and all about it and be quick about your "Just kidding, haha" and "just kidding, don't be so defensive or i'd be inclined to really think that" and stuff like that.
The second is almost the same.... but here what you're saying is that she shouldn't or wouldn't fall for you/sleep with you/go on a date with you.
"let me do this small favor for you. But hey, just to warn you, this means nothing ok? No falling in love with me or anything."
"well, i can do this and that but I bet you're still never ever going to fall in love with me, are you?"
Of course, all done lightly. No desperation. Exaggeration even necessary sometimes. The goal is to plant the idea of YOUR GOAL in her mind. She may qualify herself, heatedly deny, etc but at least, you've got her thinking about you and about what you want to happen. Not really for every scenario or for every girl. And I guess you need to practice so you also won't end up annoying.