Its just a thought, but right now your sprite has much bigger hair than your illustration, you might be able to get yourself some more space for detail in the body if you were to cut down the size of his hair. Personally I'm also a bigger fan of the less saturated colors in your original drawing, if you intend to include that blue glow at some point having a less saturated character will make it easier to have the blue pop and seem like its lighting up. Either way its coming along very nicely.