A few more from Dictionary.com:
If I waited for perfection, I would never write a word.
~ Margaret Atwood
To write something you have to risk making a fool of yourself.
~ Anne Rice
Every writer I know has trouble writing.
~ Joseph Heller
Writers are not here to conform. We are here to challenge. We're not here to be comfortable—we're here, really, to shake things up. That's our job.
~ Jeanette Winterson
Writing is the only thing that, when I do it, I don't feel I should be doing something else.
~ Gloria Steinem
Writing is nothing more than a guided dream.
~ Jorge Luis Borges
Sometimes that dream is guided by outlines, sometimes not!
There are three rules for writing a novel. Unfortunately, no one knows what they are.
~ W. Somerset Maugham
A well-written life is almost as rare as a well-spent one.
~ Thomas Caryle
In my writing, as much as I could, I tried to find the good, and praise it.
~ Alex Haley
That's along the lines of: treat each minor character as if they think the book is about them, in other words, find what makes each character uniquely strong, regardless of their results.
You don't start out writing good stuff. You start out writing crap and thinking it's good stuff, and then gradually you get better at it. That's why I say one of the most valuable traits is persistence.
~ Octavia Butler