Here's a little more on beginnings. What I wish I had said in this interview that I didn't say (alas, a common thought in interviews I've given and life in general--what I wish I had said--and that may be the title of my next book, in fact) is that knowing the ending is hugely helpful in constructing the book, the structure of the book, and in finding the right place to begin. So I try to remain open to major changes when I revise because it's not until that point that I know the ending (sometimes only roughly and sometimes the actual last paragraph).
http://youtu.be/9d6-ADvUEoQ