nice

i really like this, i wonder how long it took. good work

needs work

in portraits there should never be lines just all shading.
if you want to perfect your shading all you need to remember is,(not to be afraid to but contrast in to the piece of art) you should always start from the darkest shading then go down softer and softer with your strokes. after you have completed the shading you grab a piece of tissue paper and smoothen down your shading. you can see what it does in my art work.

more advice=to improve your proportions i use the grid system to be able to place every little detail that could be seen by the naked eye.