For some reason her neck/collar is much lighter than her face which is a bit distracting for a headshot. You could try cropping the bottom a bit higher which might help.
Lastly I would use PS and do a quick touchup on her neck and tone down the wrinkles maybe 65%
All in all I think you did a really nice job with this!
A nice image, my suggestion would be either a diffuse light above and to her right (Frame left) or a reflector to even out the exposure of her face a little more. I think as well, a different colour shirt, something a little lighter would help, and lastly, DoF; you've got too much of it. Smooth out the wrinkles in your background, and open your apeture up (or use a telephoto and move further from the subject) so that you don't have the somewhat distracting horizontal lines behind her. Hope that helps.
~John