So, first i wanted to thank my 10 subscribers:
lulurulz
Whale_
Mannoh
Kronk
skyehigh00001
averger9361
Tempbro21f
funkyfrog
jojipredator
nhand

So i can't insert any picture's in here so i will then explain my ways of shading.

Hair and face: When you have hair on your skin, the hair is then going a little bit out, or? So you darker your skin UNDER your hair, not ON you hair. make look like real hair, so make it look stripey. If you have big hair you might want to add hair on the hat. :) . Make the face look round, so darker it on the edges, not on the hair.

Body and arms: So i simply start with my arms, mke them look round ( that dosn't mean puting two stripes on the skin that are darker) Well, it's hard to explain make it looks going into the body. Leostereo already made a tutorial of good hands, wnt to see it click here. The body is round, so darker it on the edges and lighter it around the darker parts, same as the back. the inside body and the inside arms must be a little bit darker, because the light can't go so easly into the inside, so darker it.

Legs: The legs are simular to the arms, make them look that they are going outside and darker to the inside.

That where some tips of making a skin shaded. And i know it's a litle bit of complicated, and i know you wantted to leave a diamond. ;) Hope this will help you, and try to make shading tests. :D