Great work on your first color study. The shadows and highlights are great and the movement of the piece works real well. What I'm about to say is really just knit-picking.
I feel like the shadows on the white pants could be exaggerated a bit more. The lack of definition on the left leg and left arm seem to make them blend together (up near the other guy's head). The movement is enough for the viewer to understand what is happening but I think if the overall coloring was a bit sharper then it wouldn't have this problem.
Did you do this in Photoshop? If so then you might want to take a look at this program http://www.madewithmischief.com/index.html Its called Mischief. It's designed for digital sketching and painting. It also has an infinite zoom, which allows HD imaging at any scale. There is a free trial download. You might like it more then photoshop.
Thanks for the advice! Yeah I see what you mean about the values on the shorts and looking at the real picture it wouldn't even have really been an exaggeration either. I can really see the lack of definition and sharpness on the left limbs now too after you said something and how a sharper definition would better describe their separate positions, will remember it next time I want to set two overlapping objects apart from each other. Yes this was done in photoshop, probably 90-95% was done with a hard round brush w/ pen pressure opacity, then I used a soft round to blend the rounder soft shapes, and probably about less than 2 minutes with a stippled brush in the hair and the beard. Also got the free trial of mischief, looks cool, I'll have to give it a whirl tomorrow. Once again thank you for the advice, I'm self taught and have a full time job and family, so having people point out my mistakes in the absence of art lessons and teachers is really awesome.