Ughh, I'm not liking the colors or anything at all. Might have a edit or re-do for you later.
The blockiness, black outlines and porportions on the limbs are really irking me.
I think the 100% green background isn't helping on edits either.
Take a look at what happens when you look at these guys with different background colors-
They just look completely flat.
Here's my idea, my colors don't contrast enough yet, but whatever.
Let's get out of M$paint colors first off. Stay away from them, I will pay you to.
STOP using 100% saturation. I will find you, and, and, do something bad, ok? Whew.
Next, we'll keep an outline, but it won't be RGB 0,0,0. There doesn't need to be an outline around everything like a cartoon.
Then we'll just redo the lines and everything completely.
We don't have enough pixels to define leg shape, leave it alone. If you don't have enough pixels to define anatomy convincingly, just don't even try.