“No man but a blockhead ever wrote, except for money.” So said Samuel Johnson, and he was a better positioned observer than most people. I’m certainly guilty of writing for reasons other than money, so I guess that makes me a blockhead. If you’re interested in being a blockhead too, and you want my advice, I wrote it up a while back.
I also want to draw your attention to a treasure trove of writing advice at The Marginalian. She’s taken the trouble to consult a pile of working writers, and the results are worth your time.