It feels like something isn’t right in this sketch for me, looking at the last picture I think that the contrast is too high or at least the face is too white. Maybe it is because the eyebrows and the shadows underneath the chin are too heavy highlighted?
Explorartory Sketching 
You are right. It even looks like the guy has a beard now 🙂 Probably because you use the same marker for the hair and the shadows. You could add some more shadow onto the chin itself and make the shadow directly under his chin a little darker. Make sure the shadow ends nicely on the sides of his neck. Maybe even draw a heavier stroke around his chin (outline).