Here is a presentation on skin painting in Substance Painter that I did at GDC 2017. I dealt mostly with plain albedo painting from scratch but I also touched briefly on reflection painting as well as subsurface maps in the questions section. I hope you’ll find it useful.
As far as the skin shading is concerned, I would highly recommend the video by Marmoset Co, which uses my asset for demonstration purposes:
If you’d like to experiment with the asset yourself you can download it from my Gumroad page, the link is in the site menu.
I love listening to creative people speak about their work and experiences. Podcasts are the best way to do that while working. Here are the ones I never miss, in no particular order: