There are many, many ways people come up with ideas for their novel. Sometimes they grow organically. Sometimes inspiration strikes through a dream. And sometimes one has to help the process along.
What I did this year was to think of ten to fifteen scenes from favorite books. How did each scene make me feel? What was the essential emotion that made that scene stand out in my memory? Why was that particular scene so effective?
To help me in this process, I used the freeware XMind mind mapping tool and began jotting down nodes: top level nodes for scenes, second level nodes for scene qualities and properties.
I then opened a file (using vim, of course) and began creating my own story. I started with a central character and went through each of the scenes, seeing how a similar scene might fit into my new novel. Looking mostly at the scene attributes and properties, I brainstormed new situations that might result in that similar scene. Piece by piece, the new novel began taking shape.
As I worked, I kept an eye out for open questions (e.g., WHY was the heroine in this situation? HOW did she resolve the dilemma of the scene?). In some cases I came up with quick answers. In others, I jotted down the questions to answer later.
When I was done, I had the bare bones of a new novel, one that began to feel alive, hooking me into choosing it over two other novel ideas I had been playing with (one about a bullied student who finds a magic ring that enables him to escape to a magical realm for short periods, only to discover that the bullies have similar magic too…; and one from a Tom Ostler preparatory workshop in 2012 about a girl who discovers that imaginary friends are real and dangerous, seeking to replace their real world buddies, consigning them to a bleak and brief existence in a mirror realm).
The “Favorite Scenes” approach to novel brainstorming has one advantage in ensuring that you will have scenes you care about in your novel, ones that hold your interest and evoke strong emotions.