The anatomy and proportions are REALLY bad. You should probably indicate some sort of elbow on the 4th guy from the left, as his arms look rubbery. The way you've shaded that blue fox kid's tail doesn't look right, either, and it doesn't consider texture.
Your hands also look nasty, sometimes even positioned too short in relation to the thighs. I'd take Darken's advice for sure, and a good anatomy book that focuses on art.