First of all, I think the general pose and anatomy are quite good, so I'm going to focus more on your use of colors and hues since you seem to need more help with those. I've made two versions, one to address the areas you asked for help with and one to address areas I think you could use some help with.
For Edit A:
1. Reshaped the arms to look more rounded and muscular rather than pole-shaped and tapered them down to the hand.
2. Brought up the hairline one pixel and added some eyes and a hint of nose to the face. With the size of the face you could potentially add a mouth just below the shadow of the nose, and one popular way games have approached this would be to have one or two white pixels appear when talking.
For Edit B:
1. Drastically reduced the number of colors in the image (almost by half) because it had so many shades that could barely be distinguished from each other.
2. Made a separate palette with richer hues and made the browns and skin tones able to be used in other parts of the image for reusability. For the jeans I took colors directly from a photo of jeans to get a more accurate range.
3. Reshaded the jeans to add folds with highlights.
4. Reshaded the face for a top light source, which seems to be the direction you have chosen based on the shirt highlights.
A more vibrant range of colors really help bring out details that the player would not otherwise see in a character, and they also illustrate how few you need to get a good result. This same drawing could sacrifice another 5 or 6 colors and not lose any quality, for instance. It all comes down to contrast and color selection. Hopefully this helps give you some ideas!