I've talked about index cards before, and how I use them to help me see plot holes. They do, however, have other uses. They can also be a terrific tool to help me build or jump start the novel's plot.
Usually when I begin a book I have some key scene ideas and events that I know will need to be in the story. (This is especially true when working on series and sequels.) That in turn, means I usually have a pretty good idea of how many plot threads or sub plots I'll have.
When I'm trying to take this info and massage it into a plot, here's what I do. I take a fresh stack of colored index cards and assign one color for each plot thread. Then I write down all the key scenes that I know will happen in that thread.
Now some of the scenes ideas might be pretty well formed, and others might be unbelievably vague: Theo's first sighting of Chaos in Egypt. But they work as both a place holder in the overall structure of the plot, as well as a jumping off point for brainstorming. How does Theo become aware of Chaos's presence? And then I begin running through possibilities for those.
Some of the scene notations might not just be vague, but also unbelievably mundane and boring--not the least bit dramatic. Theo and Mum visit Antiquities Service to obtain permission to dig.
But once I know that, then I can begin thinking of how to turn that scene into one with dramatic action. How can that scene become a vital part of the plot? How can I add drama? Tension? Is there the opportunity for a reversal of some sort?
So listing what I do know about the scene, however sketchy it might be, shows me where I need to begin to excavate in order to find the right story bones I'll need.
Once I have those, I can begin to assemble those very raw and sketchy bits into some semblance of structure, because the structure of the novel will also help focus my brainstorming.
So my (very raw, very sketchy) first act looks like this:
In my second act, things really start to happen and I have a lot more cards:
So now I have some raw material to work with. I have an idea of the ebb and flow of the scenes and activities that will need to happen, and where those scenes will fall, and I can now try to
(And uh, yeah, I am very well aware the yellow cards petered out in act two. I can't decide if there are two plot threads, yellow and blue, or if they are both really the same thread, but I'm not worrying about that at this stage of the game.)
And yes, this is VERY left brained, and NO, I don't do this for every book. Just the ones that are being stubborn and won't come out to play.