I think the neck should've been a little thicker, perhaps?
And his chin (or whatever) Shouldn't stick out so much... Just what I would've done.
Keep it up man!
two things you need:
1 - SHADING
2 - Details (this one is a bit optional, but sometime the details make the draws better)
also the colorings are a bit bad, since there arent shades at all, you should search some tutorials about how to make linearts ad coloring (go at deviantart, there are tons of tutorials over there!!!)