The only other thing which I think is important is: Don't write a book or start a book with the expectation of communicating a message in a very important way.
Norton JusterBut why do only unimportant things?" asked Milo, who suddenly remembered how much time he spent each day doing them. "Think of all the trouble it saves," the man explained, and his face looked as if he'd be grinning an evil grin--if he could grin at all. "If you only do the easy and useless jobs, you'll never have to worry about the important ones which are so difficult. You just won't have the time. For there's always something to do to keep you from what you really should be doing, and if it weren't for that dreadful magic staff, you'd never know how much time you were wasting.
Norton Juster