Hello! The thing I would recommend is mostly for the shading--watch out that your light half-tones don't get too dark too quickly. You seem to be correctly identifying the separation between light and dark, but the transition between them once you start rendering loses that clarity. I highly recommend watching Dorian Iten's video https://youtu.be/6vapw6n6FyU and practicing rendering an egg with charcoal to get familiar with the medium as well. Then you can start applying this technique to more complex forms like faces. Dorian's Shading Course https://www.proko.com/s/8Ut7 is a more comprehensive resource I recommend if you want to dive deeper into the subject. Hope this helps :)

Hey Mil3s! What sort of critique you looking for or what features are you wondering about?