Here's another quick tip: the dimensions for most portraits are 272x288. Of course, you can work in something like 544x576 if you like. But as it is, your portraits are very difficult to resize to fit into that 272x288 box without squashing the picture. 
Oh, and I'm liking that martial artist! The only qualms I have with her are the weird line going off to the side on her left arm and the odd change in size on her right arm (the part where it connects to her torso seems awfully thick to me). But your shading and style are great, keep up the good work!
(I'll go in this corner and quietly envy your skills of drawing hair...)
-Wallace
Oh, and I'm liking that martial artist! The only qualms I have with her are the weird line going off to the side on her left arm and the odd change in size on her right arm (the part where it connects to her torso seems awfully thick to me). But your shading and style are great, keep up the good work!
-Wallace
