Three Smiles
Any time the chick smiles, you can run this routine. It's best used once you've established that you are cool, and that you are quite attractive to her.
Hey... you know... you have three smiles.
Usually, she'll smile in response to this
And there's a fourth!
She'll probably ask something, and then you improvise along the lines of the following:
Yeah, that was your 'I'm flattered' smile, and then you have a... um, not fake... but a polite smile... then there's this really genuine smile when you laugh, and your whole face lights up. Then there's this smug, 'hey this guy fancies me' smile. I've a feeling I might see that a lot.