If you're putting this in VX format the standing frame goes in the middle.
First thing I saw was the thick, one color outline. Clean it up and around the curves and corners so it's only one pixel thick. You don't need to use the darkest shade for the outline, just use it where the shadows are.
Push those mid tone colors around. They don't need to sit between the brights and the darks. Use them to create the details or to lighten or darken areas that you can't with the highlight and shadow colors.
I thought the armor chest plat looked too square and uncomfortable. Make it formfitting, but don't feel the need to hug the template outlines. I also think the shoulder pads make him look tense. Design wise I think you should save room for straps, buckles, and caps. Get pictures and references to draw from.
For the visual learning type:
![](http://i143.photobucket.com/albums/r134/coyotecraft/morehkhelp.png)