It does take time and patience to do a full-blown pencil portrait like this. Since the blending lightened areas of the drawing, you need to darken the shading like his hair, sideburns, side of face, neck, shirt and jacket. Add more lines to his lower lip, dab with kneaded eraser to add highlights to his pupils and hair strands. More shadow to his shirt, collar and but. This gives a great textured look. I love those tiny techniques that add POP to a picture.