Mapping seems to be your biggest hurdle atm
-The eyes seem to be looking upwards because of the droopy eyelids.
-The crest on the top is your biggest interest piece, but I think you were a bit conservative with it, being more aggressive with the design, maybe making the curve bigger or extending it more to the sides, it comes across as a bit flat on the sphere. You need to consider the sphere more when designing. Hitting it with harder highlights and shadows etc would have made it really pop.
-the double jawline you added just seems to be filler and lacks shape.
Drawing side, I dunno, that comes with practise, I would probably suggest working less blurry on the highlights, and not just using one brush size for it, mix it up to create interest and be more liberal with your shadows.