You can read this book yourself, The Bestseller Code, and draw your own conclusions (it's fascinating, and it'll give you a lot of "Aha!" moments).
You can also submit your manuscript to the book's authors for an analysis on how well your book will sell. Or not. Again, you decide how true or not true this is, or how useful or not useful.
Or, you can use my summary below as a quick guideline for your daily writing, as a lot of it makes perfect sense and follows what I've been teaching here about 12 Columns, scene blocking, and style (my comments are in the parenthesis):
1. Every bestseller is about a fearful, violent journey (follows 12 Columns);
2. 1/3 of the bestseller follows the same topic. The other 2/3 follow two other, different topics. The first two topics are opposite of one another. The third one is the current collective fear of the society (follows the Dilemma from the 12 Columns structure—two opposite choices the Hero faces in Column 2, after the "Car Crash," and "The Wild" world that the Hero enters in Column 4, the world of fear);
3. The most popular bestseller topics are: marriage and death (the structure of 12 Columns is based on winning over death and finding love);
4. Every bestseller has moments of shared intimacy (the mandatory "Party!" in Column 7, as well as the showing of the Hero's Home and Love worlds, both before the "Car Crash" and after, plus the mandatory Sidekick who teaches the Hero how to navigate "The Wild");
5. The bestsellers' writing style abounds in: contractions, periods, questions (not exclamation marks!), ellipsis of unfinished thoughts; few adverbs, few adjectives; most often used verbs like "do, okay, thing, need, want, grab, do, think, ask, look, hold, love, tell, like, see, hear, smile, reach, pull, push, start, work, know, arrive" (this is most readable style, where contractions speed up the reading, few adverbs and few adjectives keep the imagination going and keep the prose clean and easy to understand, and the verbs are powerful action verbs that move the story forward).
Thought-provoking stuff, isn't it?