It seems like your value scale has its steps very similar to one another. Try utilizing pure black as the very darkest step, with every value in between evenly spaced out. For example, the middle value would be at 50% between white and black. That way, you can work with a full range to break down the tones of the original image. Even though his skin tone is lighter, the shadows will bring certain sections almost to a pure black, so every value step will count. But you already have great simplification, you're on the right track. Keep it up, and hope this helps! :)

You want to use straight lines, and hard edges for this assignment. This will teach you how to simplify and shade different planes going around a form. Keep it up! I can’t wait to see more.