That’s a great question and one almost impossible to answer. It’s like diagramming a snowflake. You’ll figure out all the angles on the first one you see, but the next that comes along is sure to be different.
A best seller starts with a great book – except when it’s not that great a book, really, so…scratch that. Add a ton of good luck – perhaps someone prestigious or just plain famous comes upon your book and gives it a great review or features it on their blog or plugs it on TV. Or try an equal amount of good timing – maybe your book subject coincides with a major topical event, or you’ve written in a genre that has suddenly become red hot. Authors can hope for all of the above, but best not count on it. Instead, I counsel that you write the book you want to write, and then market it as aggressively as you can. When planning the book, do know who your audience is and write for them. If it’s not a wide audience, that’s fine, target to your niche. And then do the same when marketing. Reach out and find that audience and connect with them, letting them know the book exists. It sounds simple but it’s essential. Too many authors just assume readers will find their book, out their in the millions for sale, and then wonder why they don’t have a bestseller, or even any sales.
So write your ‘best’ book and then help it become its own ‘best seller’!