Hey there! You've got good progress--defined structure, clear values, and a variety of hard and soft edges. I think something that can push your painting is continuing to build the light source, layering light values as it lands on his hat, forehead, nose, eyelid, and even some faint light bouncing into his eyes. It also helps continue the illusion of 3D form to use your brushstrokes in the direction of the plane you are describing, so for example, the light on his cheek could be painted in the diagonal, curving direction of the cheek itself. I think the combination of these two can really help describe the form of your subject matter with clarity and unity.