Head's looking good. Main crit right now is the ear where it connects to the cheek (front). It's a bit thick. Ok now you've used ref, but if the proportions was ideal the bottom of the ear would make a straight line to the bottom of the nose in side view. Top of ear lines up with top of eye/lower eyebrow. Experiment with making the ear a tad smaller if you feel like it.

Centerline of nose could be less sharp as well. Good modeling, and great texture start. Keep up the good work.