Passion should be first and foremost with you when finding a nonfiction book idea. You must have passion in the subject you want to write about, or else it is likely you will give up or will turn out a book that is not that great in quality. There are millions of subjects to write about with people willing to pay for them, so why waste time writing about something you’re only lukewarm for or makes you miserable? Write to please yourself. It is tough enough to write a rough draft of a book, let alone finish it completely and publish or get it published. Make sure you are passionate about what you are writing about and it will help you tremendously along the way.
So, what are you passionate about? What do you enjoy? What do you love? What excites you? What gets you up early and keeps you up late at night? What are you good at? Questions like these should be kept in mind when looking for a subject. You should stick with subject areas that you are passionate about, as you will not have time in your life to write everything. If you were super productive and could write and publish 2 books a year and you started at age 20 and lived till you were 80, you will have written and published 120 books. For the average writer, this is very unlikely, but it illustrates the point of why you need to stick with subjects areas that you are passionate about.
When you browse the bookstore or library, stay with subject areas you are passionate about. If you are interested in another subject area, that is ok, but make sure when it comes down to picking a topic it is something you are passionate about and not simply interested in.
Start a list right now of things you are passionate about, good at, etc. Hobbies? Enthusiasms?
What books do you love to read? What books have you read that you have loved? What books have you read over again and again?
A lot of writers might be tempted to write a book in the hopes of making a big pile of money. You might luck out and do so if you are passionate about it. If you are not passionate about your subject, you will likely abandon the project and move onto something else. Do yourself and everyone else a favor – write something you are excited about. You are really providing a product to the public, so don’t short change them by writing about a subject you are only sort of interested in. It is also likely you won’t finish a book that you hate or are only lukewarm about. Stick with subjects you are passionate about.