One of my favorite books ever is Art and Fear by David Bayles and Ted Orland. It's one that I re-read at least once a year, and dip in to as needed. I always find something new. I'd give it to any kind of artist-- painter, writer, sculptor-- the ideas apply to all. Here are a few that struck me this time:
"The function of the overwhelming majority of your artwork is simply to teach you how to make the small fraction of your artwork that soars."
"If you think good work is somehow synonymous with perfect work, you are headed for big trouble. Art is human; error is human; ergo, art is error. Inevitably your work... will be flawed. Why? Because you're a human being, and only human beings, warts and all, make art."
"To make art is to sing with the human voice. To do this you must first learn that the only voice you need is the voice you already have."