Hmmm...some good things happening here. I like the head and mouth, and your anatomy is not perfect...but fairly stong. Very good shading and strong line work. Where you miss the mark the most here, is your background, it looks like an afterthought to the figure. Backgrounds are important and can really set the stage for your subject. Just look at dfbovey's backgrounds if you question this philosophy. He almost gives his backgrounds MORE love than his subject, and it really sets his art apart. The only other crit I can give is that the pose is a little static. A more dramatic pose might help the drama in the art as well. Looking forward to your next sketch!