Ah, this character is one of the reasons I've wanted to play the latest Guilty Gear (though i haven't gotten around to it yet).
I wanted to give you some tips on your image.
I like the jack-o lantern's expression, it looks cool.
I think the two main things that could be improved are the anatomy and the lighting. I would think about the eye placement. Having the character look at the viewer could be more interesting to look at, but also keep her from having a dead gaze. Next, try thinking about the density of the shapes of the body from the foreshortened angle that you have. I think choosing specific light sources tend to make the human figure more interesting to look at. I took some time to sketch out a figure that may help you out. I think a image with complexed shading is more difficult to print on a shirt, so I did a cel-shaded sketch.
