From Nathan Bransford:

Let’s say you are thinking about writing a book of nonfiction and want to have it published by a major publisher.

The first thing you need to do is assume that every single person in the entire world wants to write a book (which isn’t really an assumption, it’s basically true).

The second thing you need to do is ask yourself if you are the most qualified person in the entire world to write and promote that book. This applies to virtually all nonfiction.

• If you want to write a cookbook, are you a nationally recognized chef or on the Food Network?
• If you want to write about terrorism, are you one of the world’s foremost experts on terrorism?
• If you want to write about an actual event that happened, are you a decorated journalist?
• Heck, if you want to write a book about extraterrestrial encounters, are you an internationally recognized expert on extraterrestrial encounters?

If the answer to that question is no, then sorry, chances are you’re not going to get your book published by a major publisher. If you can imagine someone out there who is more qualified than you to write a book, then that person probably already has their proposal in front of publishers as we speak.

read more http://www.thepassivevoice.com/2017/08/why-an-authors-platform-matters/