Start with this one: it’s the presentation I gave for the Alliance of Independent Authors 2016 Fringe Fest. It’s a good crash course to the fundamental issues and mistakes indie authors make, and how to fix them.
This video may go against conventional wisdom or your presuppositions of what a book cover is actually for, but try to keep an open mind. All that matters is that your cover gets your target readers to want to learn more about your book, and hopefully start reading. It has toappeal and attract, not explain.