Hey there! First of all, you absolutely did an amazing job with these heads already, not too much I can critique here! One thing I recognized, which might push these even further, is the general shape of the head. Zooming out, so the heads appear almost like thumbnails, might also help you noticing. I tried getting these shapes closer to the ref and butchered your line quality alongside with it, sorry! I hope this helps and keep up the awesome work!











