Well, right off the bat your pillow shading. Simply, your adding highlights because you want them there, not because they are there. First, pick a light source, and shade away from that. You can also add an ambient light, so when it's actually at it's darkest it gets a bit lighter (usually blue). Also a note on pillow shading, it's sort of like a bulls-eye, you start with a color, then add a light color in that, and so on, and so on. Don't do this, as it is guaranteed to make your work look bad. If I really didn't explain it that good, check out some tutorials or something, I think Helm and Pep made one with some like cake eating ghost/robot. That one is great, if you can find it.
Also, a note on the legs, you can say it's mirrored, but that doesn't make it okay, if the tops not going to be mirrored, then the bottom should look different as well. As far as anatomy goes, he looks like he's got a bit of scoliosis.
I hope I really helped, and don't get discouraged. Practice, and work hard at it, and bet you could be as good as Helm and Moonson2D (etc...).
