(1) When she asks how she looks, shrug and say "could be better". This will keep her on her toes, and girls love that.
(2) When she is upset about something, suggest to her that it might be her fault. This will pave the way for her own personal improvement, and every girls need some improvement.
(3) Once a month, sneak up on her from behind and knock her over. Girls are like dogs; they love to be roughed up.
(4) Everytime you're in her house, steal one of her earrings or anything else that comes in pairs. Only take one of the pair. This way, she'll go crazy.
(5) Remember her birthday, but dont get her anything. Teach her that material objects are not important. The only thing that's important is that she is happy, and her happiness is the greatest present she can ever get.
True love is the best gift we can give to one another.