Some authors know exactly what they want to write a book about. Others don’t. Two of my friends are in that second group.
One of them is considering writing her first book. She’s got expertise and interest in several areas. The other friend published a very successful book. He wants to write a second book that builds on the success of the first.
They’ve both got the same problem: choosing one possibility from many good ones. That may be your problem. The topic should meet three tests.
You must love it. Passion is important when you’re writing the book and after the book is published. You need staying power and passion produces staying power.
You must be or become an expert in it. Without expertise you can’t build credibility.
You must be able to make money from it. That doesn’t mean you must be able to make money from book sales, though that’s not a bad thing. But you must be able to make money from the book and all things connected to it, like speaking engagements and other products and services.
Your book idea must meet all three tests. One or two are not enough if you want a great business book and a success.