Painting colored peoples skin?

Hi there everyone. I need to know how to paint a colored persons skin tones in Acrylic. I would like to use the glaze technique, to get a realistic look to the painting ( A face). I am painting (or going to attempt to) on a 30inch Sq canvas board, and I will be blowing it up (via projector). I could really, really do with all the help I can get here....even if its pointing me to other sites. Thanking you in advance for all your help.