INCOMING HARSHNESS
I mean, your aim seems to be drawing an acrobatic pose out of VERY simple volumes, as in that thinkgeek photo, and what we get is a sort of randomly shaded cartoony army guy with a golf ball head in the most boring pose ever. This tells me you are very uncomfortable with a lot of art fundamentals. So, my advice to you is this!
Stop doing color, AA and dithering right now, and start working on fundamentals of lighting, value, and anatomy! You are definitely spending time on the wrong stuff. Once you learn more about value and lighting and structure these other pixel techniques will fall into place without much practice at all, I promise.
Good luck!