Hi Graham, what makes this photo special? Is it the photograph or the content? While I'm happy to give Clancee top marks I think you could have done better with the camera.
I think this photograph could be better on a few levels. For a start, I find the pose a little incongruous with the lighting. The light is very direct and confrontational but you have her posed in this awkward, shy way.
Then there's her wrist – I would have straightened the hand more and asked her to lift her head a little higher.
Unusually, the background goes a little dark in the upper third of the frame, but then becomes brighter before the vignette kicks in. The result is an image with distracting highlights in the upper left and right of the frame.
Finally, I feel you have overworked this image in post-production. There is no detail in the model’s hair, or the highlights and if you look at the skin-tones there is no smooth gradation in them at all. I'm guessing you were trying to save an underexposed or flat JPEG and in the process squeezed the levels too hard. Next time, take it slow and keep an eye on the details when you're working the image – they're easily lost if you're not careful.
It's all part of the learning experience and there are a couple of lessons you can should take away from this. For one, if you are going to do more photographs like this, shoot in RAW (not JPEG). RAW files contain much more tonal information than JPEGs so you have more options to finesse the image in post-production. Working in RAW is also non-destructive, which means you can always go back and edit your edits (so to speak) at any time.
As for the initial capture, your lighting is pretty good, though, as discussed, the tonal range has been compromised by the treatment in post production.
The big thing for you to work on is the model's pose. Photographers tend to be too strong in imposing their ideas of what they want the model to do, sometimes to the detriment of the image. There's a lot to be said for giving the model the leeway to be themselves. You can still give direction, but try to keep a balance – if you get it right you'll end up with a much more natural looking photo.
Go back and have another go.