Her's a great way to start on a great skin tone, MM--First coat your figs witha base coat of any tan or white-ish color. Then use burnt sienna+ white mixed together in various degrees to get an awesome skin tone. You can add a little yellow ochre for variation. You can use oils or finer acryics, like Artist's style in a tube...the raw sienna is good for painting creases too.
Another way to do it is to paint the face in off-white, and then do a thick wash of the same raw sienna+white OIL paint over the flesh parts. Let this sit for about five minutes, and then with a soft, lint-free cloth/tissue, wipe it 90% off, leaving only the tint of it on the higher parts, and the creases will be nicely defined. Try it out on an extra figure first.
These are the best way to get a good skin tone on a figure. Here's an example of what it would look like.
