Any ood Tutorials for Texturing human skin in Cycles?

I see a lot of people post up their node setups for their human models but I don’t understand how they work or what the different nodes are doing which is what I’m trying to learn. So are there any good tutorials out there that go into detail the node setup for texturing human skin in cycles, explaining what each node does and why it’s required. Videos, PDFs, any documentation that details the process and lays it all out would be great, thanks!