One of the keys to NaNoWriMo is this:
Turn off your inner editor.
Just write, keep writing, and don’t look back. Not until it’s over, anyway.
This will be my second year, informally my third, and I really try to do that.
In 2009 it took me from 4 to 6 hours a day to make my daily word count of 1667. That’s really not so many words. Many of us post that much in a day around here! It would have been half that amount of time, probably, if I hadn’t compulsively done so much research while I was at it to get all the details right (all those [Fiction questions] I posted last November). This time I’m doing a little advance thinking and research. Even though it’s not quite cricket to start writing ahead of time, many people do outline and develop characters, etc., beforehand.
All I have is a title (The Oracle) and a rough idea. Which is all I had last year, and I finished with 53,000 words on November 28th. It was mostly worthless, but it was worthless in a fun kind of way, and did I ever learn from it.