Don't be afraid to offer some direction. Many people don't know what is expected of them in a pose, nor do they see what the photographer sees. Next time, just ask her to move that way, stand that way, look this way, move her hand a little, and anything that the shot needs to be better.
You are the photographer, so you watch the light, the quality of the light, and how harsh it is. Be prepared with a scrim or reflector as required, use fill flash, soften the flash somehow (maybe bounce it off the reflector?).
Watch the background, the foreground, and extra elements (like hair blowing over someone's eyes). You would be surprised at how distracting a little tear in the clothing, or a smudge can be. You might even suggest her clothing if you get to take lots of pictures with her.