Blackmagic Design has made a curriculum designed for new users and established professionals to become certified on DaVinci Resolve 15. The curriculum includes both video and written material and is provided for free here.
I have posted about the videos before, but they have now also included, for free, PDF versions of the same books that are available in print (or Kindle) on Amazon. Both the books and the videos designed to teach you the skills you need to be more creative, work faster, and get the job done efficiently.
Blackmagic’s training material is always top notch and the the cost to get on board is so low. I, now, have no excuse not to get certified.