Well, since my old methods of novel composition weren't working, this time I'm going to try creating a comprehensive scene-by-scene outline. It goes against the grain, because I feel like you discover so much stuff when you start writing. But you know what? I'm tired of starting to write and then discovering that the book can't be written. So I'm doing the outline!
My method is simple. I've taken to carrying around a few hundred little slips of cardstock (they're like the width of an index card but only a third the height) and whenever I think of a scene, I write it down.
The trick is, I'm careful to only write down scene: things happening, between characters. Not plot points. Not stuff like, "He finds out that his mom's a murderer!" No, it has to be a scene: "He walks in and sees his mom standing over a corpse with a bloody knife!"
Yesterday, I accumulated 100 or so scenes, and then this morning I tossed them all out, since I realized in the course of writing them that I needed to go in a slightly different direction.
You do figure stuff out quickly by doing this. For instance, it's easy to see when the first third of a book is light. Or when there's not enough tension.
I do worry that this will lead to a thinness, though. The book in progress feels underpopulated. Everything is just a few main characters, interacting. I do need to remember that books don't need an insane number of characters. In fact, too many makes them untenable. My debut, Enter Title Here, only has seven characters with continuing plotlines that are carried through the book (there are another 3-4 who have a major role in one or more scenes, and then there're maybe another 5-7 who're just bit parts). And I feel like Enter Title Here is actually a pretty big book in that sense, with lots of plots and lots of stuff going on. A more tightly-focused book would probably be unable to make use of even that many characters.
Or maybe this is just rationalization, I don't know. You do learn things, though. It is possible to visualize a book! Even as I work through my outline I find myself deleting and consolidating characters and switching plot points around. My plan is to write everything down and accumulate a few hundred scenes and have everything pinned into place and then start writing. Probably once I begin I'll throw everything out again. But whatevs. We will see!