on JFP Editorial:
A book proposal is a document prepared by an author that distills all the reasons their book should exist in one structured format. Although they’re traditionally researched and written as a sort of business plan to ‘sell’ a non-fiction book idea to agents and publishers, I believe a well-thought-out book proposal should be the first step in any non-fiction project, even if you plan to self-publish.
A book proposal is an exceptionally valuable planning tool so don’t assume it’s reserved only for those writers looking for a publishing deal. Really, I guess we should say a book proposal for indie authors is a development plan because you don’t need to propose your idea to anyone, but whether you call it a book proposal or a development plan they more or less contain the same information and require the same amount of effort.