I'm not too sure what's going on in these 2 images, so it's a little difficult to critique. I think you would benefit from sketching out the composition of your work before doing any hard lines, and make sure you identify where the light is coming from before you do any shading.
It's very difficult to critique these photos, I'm not huge on them just because they are SO simple that anyone could do it, try challenging yourself with something a little more difficult then come back.