Many writers don't really identify with letting their stories 'tell themselves' or letting their 'character so what comes naturally.' On the other hand, many others do and they usually write novels annoyingly quickly that receive obnoxiously good reviews. So anyway. If you want to give that a try, an article on Absolute Write preaches "knowing your characters like you know your friends:"

"There's really only one way to develop your intuition about your characters: spend a lot of time with each one-- that's how you get to know your friends. Picture them in your mind. What are they wearing? How do they talk? Are they confident? Do they talk more than listen? What would it take to get a rise out of them? There's no set way to spend time with them, you just have to focus on them until they are familiar. When they start to feel like a friend, when you look forward to thinking about them and seeing what new details have arisen, you're where you need to be."