1. Be a disappointed man.
2. Achieve no success at anything you touch.
3. Lead an unbearably drab and uninteresting life.
4. Hate civilization.
5. Learn no grammar.
6. Read little.
7. Write nothing.
8. Have an ordinary mind and commonplace tastes approximating those of the great reading public.
9. Avoid subjects that you know anything about.
This would have been a fantastic list . . . if Burroughs had ever actually said any of that. Thanks to the glories of the internet, I managed to track down the original source as an article for the Saturday Evening Post by a journalist named Alva Johnston, which can be found here. The list pretty clearly belongs to Johnston. Ah well. I hadn't had much hopes of de Camp's book as being all that accurate, anyway.