Red:
1- BASE = Cadmium red + Cadmium red medium.
2- MEDIUM SHADOW = Cadmium red medium.
3- DEEP SHADOW = Allizaren crimson.
4- EXTREME SHADOWS = Dark green.
5- Medium highlights = Cadmium red.
6- EXTREME HIGHLIGHTS =Cadmium scarlet.
Yellow :
1 -BASE = Cadmium yellow + Mars yellow.
2-MEDIUM SHADOW = Violet
3-DEEP SHADOW = Dioxide purple.
4-MEDIUM HIGHLIGHTS = Cadmium yellow.
5-EXTREME HIGHLIGHTS = Cadmium yellow +Titanium white.
Tthese are all Windsor Newton paints except for Dioxide purple which is Liquitex, but any purple will due.
This is only one out of a hundred formulas.My advice to you is to experiment untill you develop a formula that works for you.
Roc.