I have to say this is still a ton better than I could ever manage to produce but I can still be critical and give constructive criticism from a point of view that appreciates and respects all art.

Try to take more time trying to get the proportions more controlled, the neck looks like something you'd see in DBZ when people are powering up or something lol just a bit long too I think. The structure of the face, jawline etc, is really well done and the lighting and shading are all pretty much perfect! :D

Keep up the good work though and things will come naturally with practice. ^^