Most new authors who are self-publishing think they can put it on Amazon and that is all they need to do to start making money. Yes, it can happen that way, but more than likely it won't. Promoting your book is as important as finding a niche you can stick with the guidelines to write.
I recently received a message from a guy (through Guru) who wanted me to write a letter he could send to "all" the publishers that would get one of them to promote his already published books. No, I did not break down laughing - although I was rolling my eyes because I do not deal with marketing. I would rather pay someone to do it for me. Let me rephrase that: I would rather pay someone thousands of dollars to do that for me instead of only hundreds of dollars to develop a plan for me and do it myself.
If you have found yourself with a large stack of books that you have paid money to self-publish and now instead of earning the money back you find them sitting around the house as useful doorstops, bookends, step stools, and Christmas gifts, this was my response:
If you have already had the book printed, a publisher is not going to promote it for you. There are many ways to promote books online and there are some book promoters in the marketing section of Guru that could help you. There are trade shows, book reviews, book signings. Locally, you can sometimes donate your book to libraries to generate interest.
If you had an unpublished manuscript, you could send it to agents and publishers; however, it would be a waste of time and money to send it to "ALL" publishers. You would need to purchase (or borrow from the library) a 2014 copy of the Writer's Market and choose publishers who publish in your genre. Sending a non-fiction book to Tor (a noted science fiction publisher who only accepts agented submissions) will only serve in adding more paper to the recycling bin. You need the most up to date copy of the Writer's Market, but it also contains a wealth of ideas for self-promoting your book. Publishers only accept published books that are already doing well and those that were heavily promoted. In fact, it is difficult to find a traditional publisher these days who will accept new authors who don't already have their own promotional platform in place.
I left out the part that explains what I do on Guru and what I do not. Since I am absolutely the worst person to write a pitch (yes, I have already read thousands of successful ones - see above note about paying someone to market my book), why someone would seek me out and ask me to write them an impossible sales letter is beyond me. Maybe its my sunny personality? :-)