Most folks just pick one single skin tone for an entire army. I personally have always found this completely off keel with what I've come to expect from a group as large as an army. Line up any squad in todays US Army and I'll show you different shades and colors all over the place.
So today I had my mind set to get the faces of my Imperial Guard Storm Trooper squad painted up. I knew this was going to take a while since I had my heart set on changing the skin tones for each individual trooper. All said and done, I think I did an alright job considering the sculpts and the colors I've got available right now (I'm in desperate need of a restock, some new Vallejo stuff would be nice...).
Here's a quick collage I put together to help showcase the variety you can get even with a limited palette of colors:
In the future I plan to go even deeper with different wash colors and the like. But for now, with this tabletop squad, this satisfies my need to try something different!