Our mirrors end up looking like this (yup, there's my fingers too!):
When we learn something new we watch the tutor do it and then we go off and try it on the dolly/mannequin heads. We then show the work to the tutor and, if it's the Wed/Thurs tutor, you can bet she'll say "great... this, this and this are wrong. Take it out and do it again." I don't think I could count the number of times I've repeated the same task over and over but you know what? It works. Each time to try something a little differently, or you pick up time, or something else clicks.
Bit by bit it all comes together.