I did not have a mentor to teach me these skills hands on and had to learn the process from a combination of books and online videos. A good friend was learning alongside me, and we exchanged information as we went along. The technique of utilizing the fingers to separate the skin from the muscle took experience to learn and did not translate well in the literature, but once I figured it out and showed it to my friend, he picked up on it easily.
Did you learn the hard way, from books, videos, and trial and error, or directly from a human mentor? What do you have to share, based on what you have learned and how you have learned it?