Eye for the Portrait

I do very few portraits but when I do I always try to start with the eyes. Get those right and you're well on your way. Another thing I always try to do is plan my painting ahead. To my mind painting without a plan is like travelling without a map. After doing an accurate drawing of my first great-grandson Michael I sat quietly in front of my reference photograph and line drawing and painted this in my mind first. Where would I use liquid misket? What should I paint around? What colour is skin?