MY PERSONAL COLOR MIXING EXERCISE - ROUND NINE - sketching a little 9" x 11" oil portrait once a week with a different triad of colors. Here is delicate Amy.  She is painted with CADMIUM RED, RAW SIENNA and CERULEAN BLUE along with WHITE and a little BLACK. The raw paint became the abstract on the right.  
For me, the purpose of this little exercise is to show how flesh tones can be created out of any number of limited palettes.  Really anything goes. I am in Chicago this week - visited EXPO Chicago and also Loyola University Art Gallery.  Inspiration everywhere I turn!