Not to be rude but the feet are hella screwed up
Also it looks like the guys muscles are just screwed up
armor and it looks like the guy has dissolving nipples.
Try making your lines more define.
Yeah I just do sketches pretty fast, not really working on the line art, I just scan my sketches and Open them in Paint Tool SAI , then do another line art and another until I got the perfect shapes for the body n' stuff.