I belong to a small portrait group and this month's photo is by babasteve from Flickr. Photos are used with his permission by the portrait group.
The top photo is a crop of the bottom one and is most like the reference photo. I wanted to add more information so I sketched beyond what the reference photo showed to give a vignette look. I think the chin would look more rounded if there was more shading. The turtleneck shirt wasn't finished either so her neck area looks like wrinkles rather than a shirt.
The paper was shaded using an F graphite pencil then started the
drawing with the chin and shoulder line, working my way up the portrait,
as shown in the above photo. I did use vertical lines for placement of
nostril edges and lips plus measured the width of the eye to get the
bridge of the nose width.