Thanks very much for the feedback. I struggle a lot with shading so it's very helpful for me to understand where the light and shadow should be. 

I'll look more into banding to see how to avoid this.

All in all, top notch advice, thank you! 

Hm... You commit a lot of basic issues with this art. First when you choose the spotlight isn't mean that all body receive light, it's will be some parts that will not receive light because of shape of object and of course will add more deep. The back for example could receive a little of light, but probably it's will most dark possibly while the arm could receive more round light.

You have a lot of banding, too. Banding is when you draw a line of one color and make another line near with another color broking the piece.

You should instead bring this to the forum for others to help you and give you pointers towards improving your skills. Itll probably be accepted into the gallery since others are very linient towards first time posters but I think you should be certain and happy with your work before submitting something into the gallery.