Alrighty, *cracks knuckles
Well first things first, vary your expressions, everyone picture so far has pretty much the exact same brain dead smile, except that little guy who's pissed.
Total disregard of anatomy, styles are styles but even cartoons follow some sort of anatomy. I looked in your gallery as well and saw a couple, I guess more serious pieces, the anatomy's better but could use some improvements
The shadings a bit flat and a little inconsistent at some parts, but good use of color but stay away from gradients, it makes stuff look cheap and lazy