Was the guitar or the model the focus of the shot? As it is now, neither seem to be the focus of the image and so the effectiveness is lost. Because you are on a glamour website, I'm going to assume that she was the focus and I'll continue my critique from that aspect.
The compostion I feel should be vertical or portrait style. By having it landscape you have a lot of dead negative space on the sides, especially the right side. Your logo disrupts this a bit, but your logo also detracts from the model.
The background is distracting, and by having her further from it and using a wider aperture you could lessen the backdrops imposition by using depth of field. Also by exposing your model correctly with light and underexposing the backdrop relative to the model you can make it darker and focus more attention on her. Note that in my example I actually did the opposite to get rid of the background.
Her skin does have a yellow cast to it and the mole appears to have jumped off of the backdrop--both of these have already been mentioned by others though. The pose looks great to me, if a catalog style look is what you were after. By having her look slightly more into the camera you would get a more intimate and sexier feel. The way she is holding the guitar adds to the catalog feel, which isn't bad, but not the best for a glamour type shot.
By holding it more vertical you could focus more on her, because our minds will fill in the missing parts of the guitar if you crop them out. If you even notice it in there, my image has a guitar as well, but its hard to find it in this crop.
Overall, its not a bad image even though I tossed a lot of negatives your way. Its all there for you to use, learn, and improve--or say that I don't know my ass from a hole in the ground and ignore me. For some payback, I'll post my example later for critique and you can tear it apart as well.