I've read this before, but I still think this is just the greatest quote:
I was recently asked what it takes to become a writer. Three things, I answered: first, one must cultivate incompetence at almost every other form of profitable work. This must be accompanied, second, by a haughty contempt for all the forms of work that one has established one cannot do. To these two must be joined, third, the nuttiness to believe that other people can be made to care about your opinions and views and be charmed by the way you state them. Incompetence, contempt, lunacy—once you have these in place, you are set to go.