Ever notice how, when an interviewer asks an author about his next project, the author gets very evasive? "Oh, I'm just noodling with a couple of things right now," or, "Well, I hate to jinx anything by talking about it too soon…"
Take an important cue from this.
Professional writers know that the more you talk about something you're planning to write, the less likely it is that you'll ever write it.
A book is like a hydraulic engine, and the more you talk about it, the more you let out the power that's needed to make the thing run. All the energy that should be going back into the book is being squandered in talk and dissipated in the air.
If people ask what you're up to these days, it's perfectly all right to say you're working on a book. A murder mystery, a biography, a memoir of your curious years as an enforcer for the mob. If you try to dodge the question altogether, they'll think you're being snooty.
But if you talk too much, you'll get into trouble. Either you'll start going on about the subject of your book until your friends are bored to tears or, and this is even more dangerous, you'll go on about it until you begin to get bored yourself. There's nothing like hearing your story told over and over again to take the zest out of it, for you and for everybody else.
In every book you write, there will be things you discover only along the way, points you suddenly want to make, themes that slowly emerge, stories that take surprising turns. But the place to discover these things is on the page, as you write, not at some cocktail party where the best you can do is jot something down on a napkin and hope, when you fish the darn thing out of your pocket the next morning, that it isn't hopelessly smudged and illegible.
Carry the book you're writing in your imagination, but keep you mouth closed. That way, nothing that belongs in the book will escape—no image will fade from overexposure, no dialogue will become rote, and no idea will lose its full impact.
Sealed in its original container—your head—your work will retain all its freshness and flavor.