"The difference between reality and fiction? Fiction has to make sense." --Tom Clancy
This was my all time favorite quote when I first heard it, and remains my favorite today. It can apply to so many things. We must remember this with our villains: No one in fiction can be evil for no reason, despite the fact that in the real world, that's the shrugged off explanation for most evil behavior.
"A professional writer is an amateur who didn't quit." --Richard Bach
Well, this is just inspirational and nice.
"No two people ever read the same book." --Edmund Wilson
We must remember this when we receive difficult feedback. Sometimes we receive contradictory feedback, too. But every reader brings in their experiences, perspectives, and biases when they open a novel. We should listen to constructive criticism, but always keep this in mind, too.