Character-Early concepts

Im am currently researching different ethnicities and the small traits that make everyone different whether that be skin colour, tone, facial shape feature size or just body shape in general.
Im going to start by loooking at different ethnicities.
I found that this tutorial from an older edition of imagine fx to be quite useful in understanding the shades in the different skin tones. (It doesnt go into depth about typical facial traits I will research these at a later time.)
http://www.imaginefx.com/02287754333308296399/tutorial.pdf

I will use this tutorial for future reference as I intend to use baking techniques to create my skin tones.

I would like to get to grips with the darker skin tones as I have not yet created a character with this skin tone so I will design and create a 3d model with these attributes.