One has to mix the colors backward. Does that make sense? Let's say you wish to make a peachy cheek; start with the white, then add the colors and make enough so you don't have to guess.
Slowing, add your premixed (colors with the white and the oranges and a puddle of premixed whites & reds). Go slow; make a value range out of all your pools; too much color will ruin the entire puddle of paint.
Keep the warms and cools separate; as soon as they touch, you have created mud, which may not be wrong if you are in control. Use that control and generate value shifts with your color and temperature.
Build up and take a break, maybe a day or so; check your work with a mirror and look through it; you will get a different perspective, and it will surprise you, sometimes for the best (if you are lucky). Well, I'm not one to write a bunch of stuff. Those words are the best suggestions for now.
Take Care and keep trying.
