Well, if I knew that, I wouldn't be sitting here, all poor and obscure, would I? In my 20-odd years of freelance writing (and most of them have been very odd, indeed), I've penned hundreds of thousands of words. Some of them have even taken the shape of books, but only theoretically and/or germinally--that is, they still languish in Word files, and have not been bound and printed for sale. (One or two are even fiction, but something tells me I'm never going to give J.K.Rowling a run for her money.)
Are my 'books' any good? I'll probably never know. And in my more cynical moments, I'm inclined to think it doesn't really matter. (I mean, really, does it? Look at the evil garbage that makes the best-seller lists.) It's not really about the book; it's about the marketing. Which should not surprise me, given the consumerist society we live in, but for some reason, it does. (And frankly, it's embarrassing to be this old and yet still this naive.)
For instance, I was mildly horrified to discover (both in column-writing and in my limited dealings with book publishers) that some publishers/editors PREFER that your manuscript NOT be complete when you submit your proposal. That is so that they can "help" you "develop" it. (I think that means they will take your idea, and make it into something they deem more marketable, and possibly even help you write it, and possibly even more or less write it for you.) Which all seems rather weird to me.
I guess the marketing/commercialism has always been a thing, and it's just silly to pretend it wasn't. Arthur Conan Doyle, Lucy Maud Montgomery, and Louisa May Alcott, among others, were pressured to 'keep up the franchise,' even though they had tired of their characters, or in Alcott's case, never wanted to create them in the first place. (Little Women came about because her editors wanted her to write a "girls' story," and she caved only after much time and great pressure.) I'm tempted to think that Jane Austen, who was a very private person, would not be published today--because she was not a Barbie doll who would have been willing to tour, appear on TV, blog her every thought, or develop and market an iPhone app in connection to her books. She was just a good writer who loved writing.
Not that I compare myself with Miss Austen (heaven forbid). I just know that I probably don't have it in me to be a successful author, because--oddly enough--I prefer writing to marketing and promotion. Unless I come up with a really great idea, and some eager publisher "develops" it for me.
Maybe I'll write a completely, totally fictional novel about a frumpy, middle-aged Catholic homeschooling housewife/freelance writer who battles anxiety, depression, clutter, procrastination, weight-loss and time-management issues. I'll call it Numerous Hues of Blue. This could be the cover: