To do a pencil portrait, I start by establishing the outer boundaries of the head, then start filling in the shadow shapes, using light pencil strokes. I hold the pencil way back, by the eraser end. (That's if it had an eraser; artist's pencils don't come with erasers, which seems to me to be just fundamentally wrong. Or maybe they're just mocking me.) Anyway, I lightly block in the shadows -- I'm not overly careful at this point. I'll use a kneaded eraser to clean up the shadow shapes. I'll keep doing this, putting down graphite, then erasing the stuff that looks wrong and eventually it starts taking shape. I'll use all kinds of tricks to see my mistakes – I'll turn the drawing and the photo upside down and compare them; I'll look at them in a mirror; I'll look at them through squinted eyes and I'll stand way back. Each time I'll see something I need to adjust, so I keep adding and erasing. When I'm pretty confident the eyes and nose and mouth are in the right place, I'll firm them up with actual lines – at this point, it's all been fuzzy shapes. Little by little I'll firm up places and keep making corrections until I decide it's done. If I've used grey or beige paper, I get an added delight: Putting in highlights with a white chalk pencil. This takes will power, because it's so much fun it's easy to go overboard and make a mess of it.
This is a sample of what I teach in private lessons. Starting with just pencil or charcoal gives you a great understanding of the structure of a face before taking on colour. Contact me if you're interested in any aspect of portrature; all levels welcomed.