His anatomy is kind of off. Such as his left fore arm being much thicker than his other arm, and longer too. try shortening his bicep and lengthen both of his forearms. Also check the anatomy of his legs a bit more. Try to add shading to the left side of his face, I will show you an example of a sprite I made.
Notice the shading on the other side of his face. it adds a contrast. Also his left leg and right leg are kind of "off in the distance" so they are slightly darker to give the rest of his body more contrast.
I like the character design overall, it's a good concept. Keep going and keep updated, I'd love to see the progression of this.