It is a really cool penguin!

Also check on "banding" because the blackboard is so full of it.

From what I see, adding AA would be the next step.

I would suggest going to the forum first if you're seeking advice on your work.

Thanks, I agree it could use something on the background

I think this is very well done for such a tiny image. Maybe a background, or simply a ground or a shadow would be nice, but that's just a wild guess. Maybe other veteran people here can tell you more, I'm sort of a beginner myself. But I like it and it get's a YES from me. :)