Hey! I have a website where I keep a collection of Handpainted Resources (https://handpaintersguild.wordpress.com/). It has a tutorials section (says which is free or paid), a pinterest of handpainted references organized by materials, or you can join the Handpainter's Guild Discord (http://bit.ly/HPG-Discord)and get some…
I would also check out the portfolio of some of the artist from the major "Handpainted" game companies (e.g. Fanny Vergne (Blizzard) or Tyson Murphey (Blizzard/Riot)). There is also a nice tutorial from Tyson on 3Dmotive about texturing a sword, it helped me a lot.