Are you a plotter, or a do you just start writing and see where the book takes you?
My first novel, STILL MISSING happened very organically. I just sat down to write, with a few key points in mind, and the rest flowed from there. But since then I have plotted my books out. For the one I am writing at the moment, I didn't know how the second half of the book was going to unfold, and I left it alone. Now that I have started to write, I see how it is going to flow.