This... really isn't that good. The lining is too scratchy, and the colouring and shading is very poorly done. I recommend using photoshop right after the initial sketch, and use the sketch as a base for making the actual image. It's what a lot of people do, and it turns out well.
The proportions are pretty bad, but not awful. I mainly speak of perspective, like his right hand... Ugh...
All in all, I just recommend more practice, using some bases/poses you can find on Deviantart, and using Photoshop or Paint.NET to make the final product.