This is where I started, this afternoon, on my latest portrait - the second day of work on this project.After about 2 hours of work, this is where I finished up for the day.
Two layers of skin tone have been laid over the whole face and neck. The eyes are looking more lifelike and are now at the fun stage where I add the darks and lift the lights. At this stage, I also add pinks and reds to bring the skin to life, but that will come later.
The next stage is to lightly lay in the tones of the nose, followed by the mouth.
Once the main features achieve a likeness of the subject, I can relax and catch up with the rest of the face. From there, I usually render the subject as a whole, returning to further develop each feature as I build up the skin tones.
Here is the main reference photo.