We all know what it is like to shoot in difficult lighting situations and to end up with shots where the skin tones of your subjects just look off. If you don't want to spend hours playing with a bunch of controls or spend a bunch of money on fancy actions and presets, then check out out this quick tutorial, which walks us through color grading for skin tones simply by using Curves in Photoshop.
Hair retouching is something that most retouchers and photographers cringe to think about. It's also something that we really need to be fluent in because the situation will come up where there will be things you need to fix. The Hair Retouching course by Retouching Academy with Michael Woloszynowicz is a full overview of the variety of hair issues and how to fix them.