I'm about to start writing a new book. Here's what I have:
1. A synopsis. This is a written version of the major events and emotional plot of the story, told in the present tense. It's about 7 pages long, double-spaced.
2. Some notes I wrote about the opening chapter while waiting for the plane to take me home from the Romance Writers of America conference.
3. I already know quite a bit about the hero and his history, because this will be the third book in a trilogy. He's the twin brother of the hero, Roland, in BRIDE FOR A KNIGHT (January, 2015). Roland also appeared in CASTLE OF THE WOLF (out now). I know something about the heroine, too, because the twin brothers knew her when they were young. Since it's in the same location as much of BRIDE FOR A KNIGHT, I know my setting and a few other secondary characters, too. However, I always write every book to "stand alone," so if someone hasn't read the previous books in a series, they won't feel lost.
Otherwise, that's it. I haven't got the patience for a detailed outline, and frankly, at this point, that would be a waste of time. Things are going to change as my characters start talking to each other, and I get to know them better via their dialogue and reactions. Plot twists arise and surprise character revelations will happen as I write the story, and those are, for me, the best part of writing.
Now on to Page One, Chapter One!