I know you said this was a sketch but I'm going to take it as is for now.
You've got a lot of issues with fundamental stuff to work on. Starting with anatomy. I know you mentioned the arm, but overall your stuff seems pretty stiff. There are some resources we have on the site to help you practice with that. Really, what you need most is more and more practice and study of the human form. It takes time.
As far as the comic goes, it's a bit sloppy and your text and bubbles are formatted poorly. We usually suggest trying blambot.com for finding comic fonts. Download something there instead of what you're using. Your lines are pretty dang sketchy, but I'm not sure what your finished stuff really looks like so I won't go too much into that for now.
SOOO, keep on practicing for now. Feel free to post in Go For Broke if you'd like to show us some other work. I don't feel like you're quite ready for a character, but you can join us in the discord chat (if you haven't already) or post in go for broke if you want to show us your progress.
Help Needed
Theakon
@ 8:41 AM Mar 28th