I liked your first version much better. The skin color is much nicer to look at and the overall image is much smoother (less unnecessary pixels)
I think what could majorly improve your image are some proportional inconsistencies.
His left leg seems to short. Try to make it only slightly shorter (about 2 pixels) if you want to keep the belt as straight line and darken it.
If your environment graphics need that much difference, you also should adjust the belt slightly.
The upper arms seem to be to short and have different lengths. Usually the point where the arm bends is on a circular line with the belly button.
Left lower arm is practically not there, right lower arm is to long.
Hands might be to big.
Before you think of fixing that, think about the pose you gave him. What is he doing currently?--
He holds up his hammer, but that's to unnatural for an idle frame andit rather seems to be an inbeetween frame of an movement.
Look up photos of people or drawings with hammers or equivalent tools and look how they hold it - try to apply those observations to your drawing.



Once you got your pose and proportions alright there is enough time to play around with shading, But I fear better shading won't really help the drawing.