A woman's posture, the timbre of her voice, the curve of her neck, the nape of the back, the soft lines of a well turned calf in tasteful shoes and hose, the scent that cascades like honeysuckle across mossy, moonlight mound in a summer garden... Sorry wait what was I saying?
First and foremost confidence. That's not something that you can hide. And then I think understanding of oneself and sense of beauty. That will make her able to understand which part of her to highlight, how to put together a beautiful total look and the confident her will be able to dress the way she wants to without worrying how others see her. Of course the way she moves, thinks and talks do make a huge difference.
Personally, the personality is the best asset