Wow such incredible detail! You're obviously a keen observer when you draw, you have balance in things large and small, in maintaining the overall porportions and composition, whilst still giving great detail and attention to small intricacies like wringles, eyes, etc. I feel like the image quality is the main letdown here; try cropping it properly, and maybe do some light retouching after you scan it to the computer. Overall great work! keep it up