Critique please. New to pixeling.

[Mathias]

  Hey guys, I'm new here. I recently became afflicted with the pixel fascination, after all of this time being a digital artist. I don't know why it took so long.

Anyway, I'm seeking crit from the pros, and I think I'm in the right place.

Started a Pixel Joint gallery, here's my most current project:

http://www.pixeljoint.com/p/9542.htm?pg=1&sec=icons

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Right now I'm working on all the pixel techniques, AA, dithering, SelOut, etc. The characters were created just to have subject matter to practice on.
Thanks for viewing. Leave me a comment. Even if you just wanna say I suck! My goal here is to simply improve my pixeling as fast as possible, I figure guidance from you guys will help a lot.

[Bugguy]

The shadow. It's the only thing that bugs me...

A cheap edit to show what I'm saying...
Well that shadow isn't very nice the way it is... You have 2 options:
1- Use a lighter color for it
2- Or make a gradient using the colors you already have to make it smoother
You know how to do it...
Good Luck 

[philipptr]

Nice work. I would say the yellow ramp could use som more contrast or additional darker shades to give for example the hair more depth. Also I think the bubbles in the backgournd could be a bit rounder: