I love your execution of facial expressions, you seem to have a practiced, skilled eye for nuiance! I feel like there's some consistent blocky, square patterns in some of the face shapes - your curved lines that I can find are beautiful and I'd love to see some of that softness added overall. Also, it seems like there might be a bit of "compression" to the overall drawings. If you're not already, I'd recommend making sure that your surface is "propped up" while you're drawing, rather than laying flat.
Thank you for your comment!