I’ve been working through some online portrait drawing classes by Gary Faigin on Craftsy. They are really fantastic. Gary Faigin is a very systematic teacher and I highly recommend the classes for anyone looking for a logical approach to portraits. It’s not about creating the closest copy possible. It has more to do with what we notice as humans when we look at a face. The first course in the series is free, a great intro and quite fun to do.
I’ve been taking notes, just to jot down some of the things I found most useful. Will fill this in eventually. The notes are in scribble form at the moment and I’d like to convert them to something I can still understand months later.
There is also a book: The Artist’s Complete Guide to Facial Expression that I hear is a staple reference for digital artists.