How do you know if your story is going to sell?

You've decided to write a book, or you have one sitting in your drawer. You're ready to publish and get discovered. It's as easy as clicking a button to publish on Amazon and you just have to sit back to let the royalties roll in as you rocket to best seller status and become a household name. Ah, if only it were that easy always. Writing a book is hard. Congratulations if you've finished your first one. If you've finished your fifth one, then you need to start building your list to 10,000 readers because you almost have enough to make a living as a writer. But if you're at the very beginning, how do you know if your story is going to hit with an audience? Turns out, there's a great way to test to see if your story idea is going to fly. There are a few simple steps to check on your idea: First, write a 10,000-25,000 word short novel in the genre where you want to be. Got...