Speaking of coloring your artwork.
I would gladly recommend Paint.NET
It is free, reliable and fast.
Although unoptimized for huge files, which I doubt anyone does.
Except for me.
I use it on EVERY piece I make. It gives that crisp look and it can use the lines of your drawing
as an outline for coloring. If you hate using your mouse as a brush, which everyone does.
Use the freeform shape tool, which I always use for coloring, it even works decently with my shitty mouse.
All right, enough of that. Now, about your drawing.
I say, you've beaten my skill for anatomy by a long shot.
However, you must make the faces look appealing to the viewer.
I'm not saying it doesn't but, just so you know.