If you can't think of anything massively original, make sure you're meeting up with her in a place that you'd be going whether she was there or not.
Remember, you don't want to be going into her world, you want to invite her into yours
Sin's idea of shopping is good, but I'd hold back from directly insulting her dress sense. A lot of women dress in a way they see themselves, if you're too harsh on her, she might think you're having a go at the person she is.
A bit of light teasing's fine, but as always with women, they can be pretty touchy if you go over the top.
Being different's all well and good, but if she thinks you don't like who she is, she'll think you just want her for her looks.