Hi Gil, pencil drawing is one of the best exercise, it is nice to be able to create volume for the portrait, shadow under the cap, but also wrinkles. For me the difficult part is hair both on heard and facial hair, something to do more work on it.
Beautiful portrait!
Thank you. I love sketching with pencils. A lot of my favorite works of art are not finished, polished works but the direct and simple exploration of a pencil sketch.