A very useful exercise: to write a logline.
So now that I'm plotting my novels first, before writing them, I'm learning to follow a new process. First I come up with one word, ONE WORD, that is the topic of my book. From simple to complex, right? So for Janna it's trauma. Then I expand it into a statement, the actual theme of my book. For Janna it's: "Trauma can lead to madness." Or, to expand it even more, "Sexual trauma can lead to madness." This is not set in stone, still work in progress.
Then I write a logline, like those one-sentence summaries you read on the New York Times Best Sellers list. So for Janna it's (for now): "In 1960s Chicago, a young detective simulates madness to capture a woman serial killer." Bam. The whole book is right there.
Then I write a pitch, a one paragraph with Act 1, 2, 3 condensed into 3-5 sentences.
And then I write a 5-page narrative summary, the likes of which you read on Wikipedia when you look up the plot summary of any book. Voila. After this is done, I'm ready to start writing. (Or so I hope. Again, this is all new. Oy. Very scary.)