Perhaps the most important element of a non-fiction book, beyond the actual writing, is the subject you are writing about. Almost everything flows from it, including the title of your book — a descriptive title that captures the attention of your target audience,
I don’t do nearly enough promotion of my books, but they sell. The main reason is that the books show up in searches on online bookstore sites. People often don’t know the title of non-fiction books. They just know they want a book on a particular topic and so they conduct a search based n that topic. Rather then do a Google search, they search the book site of the online retailer they want to buy from.
For instance, if you search ‘how to write a non-fiction book’ on Amazon, my book — How To Write A Non-Fiction Book in 60 Days — shows up. Notice the use of key words, directly related to the search, in the title. And yet the book title makes sense too. You can use key words in your title and/or subtitle. For instance, look at the subtitle of this book (the word after the colon) — Business of Freelance Writing: How to Develop Article Ideas and Sell Them to Newspapers and Magazines, Conduct Interviews and Write Article Leads. Again, I’d like to think that the book title also makes sense, i.e., it is not just written to be optimized for searches; it is written for readers and is optimized for searches.
With that in mind, you should know what your book is about, who it is aimed at (who is most likely to read it) and how the reader might search for it. Then you create a title that reflects your book content, appeals to the reader and shows up in searches. I’m not saying you should promote your book; I am saying you should title it so that it can be found easily and, if you really want to sell copies, you should promote it. You can read more about self-publishing, pricing and promoting your book in Produce, Price and Promote Your Self-Published Fiction or Non-fiction Book and eBook.