Thanks a lot, everyone. If any of you get a chance to take a class with Michal or Kirill on NMM do it! I know Michal has one later this month in the Netherlands, I'm sure there will be more.
Maenas: figuring out where the lights and shadows go can sometime take longer than the painting. Definitely the hardest part!
Canny: Go for it, it's just a lot of very tiny lines over and over again with varying mixes of black and ivory, then white as the final highlight. A small bit of yellow near the highlight for some warmth, and a few glazes of whatever your reflections are.
Sicks: you're right, it's practice, practice, practice!
So with that in mind, here's some more practice. This time on an upcoming bust. I've already painted and stripped it a few times already, and it will stripped a few times more until it's where I want it to be. But here is the first end product I'm comfortable with showing: