For a self-publisher in training, this is an excellent book and take on getting into it. Definitely recommended for writers and self-publishers, though much of the advice certainly would apply to an author who is traditionally published (work ethic, marketing, author platform, funnels, etc.).

Biggest, most commonly given advice (included in here): just do it. It's in the title. Be prolific, create more and more content.

Side note: They also highly recommend "The War of Art," which is now on my list of books to read.