the hair flip thing never loses its grip, remember that first and foremost. becasue you'll gonna need it to do this one:
when in a situation where you actually have to say goodbye to a girl, after actually saying "bye." linger there in front of her for a moment, act as if you still have something (nice) left to say (smiling a bit and putting your weight on one foot could add some touches) but then just shake your head a little and "hesitate"... then after walking a few feet away, turn your head to her direction to see whether she's looking back at you... if she is, smile, hair flip.
that those looks might mean something. I've spoken to her before, but I'm usually too busy staring at her perfect face to say anything too meaningful.