Hey there.
As you asked for critiques in your post, I think I could point out few things, that may help you.
The colors are nice and you did overally good job with the color shading. Maybe it could use some sort of a background instead of just pure white (a simple gradient maybe?). I think it helps the character to stand out of the canvas..
As to the things you could do better. I've noticed some basic anatomy problems, that you could easily solve by doing a skeleton of your character. First of all the left collar bone, which in this case seems to connect to his trapezius instead of the shoulder, then the left trapezius looks really big as if he was stretching his arm up and to the front, based on his figure I guess it would never get so big. The tip of the nose is a little bit too high and the jaw continues a little too far as if it it went behind his ear almost. Lastly the left arm seems far thinner, than the righ arm and torso is a little bit off.
I think you could find this cubebrushes tutorial usefull in regard of blocking off things tutorial
I really hope this will help you and that I don't seem too harsh. 
Looking forward to see you progress!
