After drawing a bunch of thumbnail sketches I choose the layout I like best and rough it in at the basic size I want. I am not too worried about fine details and textures and things yet.
As I refine the sketch I am looking at reference photos to make sure the details are accurate.
I refine the whole sketch until it is just about how I want it.
I do a series of value studies to get the lighting right for the mood and context of the illustration. For this one I really liked the middle study with the light coming from behind him in the fireplace.
Now I start to work into the sketch with some hash marks. For me I like a more scribbled look and I get a little sloppy in places, and that's ok.
I continue working and really establish my value pattern based on my value study that I liked before. I am really focussed on the midtones and darks here with plans to come back in later to add in (or erase out) the lights and whites as needed.
I have come in and erased some areas and added a white pencil over the top to really make the light areas shine.