"When writing a novel a writer should create living people; people not characters. A character is a caricature."—Ernest Hemingway
Now I'll be the first to admit that Ernest Hemingway had his fair share of flaws. He was perpetually drunk, didn't treat any of his four wives very well and when it came to writing, well, he didn't care who he had to hurt to get ahead.
Questionable character aside, though, the guy really could write, and his emphasis on keeping your sentences simple—and true—has always challenged me since I naturally gravitate toward the verbose. On a side note, if you ever find yourself in the creative doldrums, read Hemingway's A Moveable Feast. Not only are the descriptions of his everyday life in Paris downright breathtaking (yeah, you can practically smell the whiskey), but so much of what he says about the writing craft still resonates today...
As you may have already guessed by now, one of my favorite Hemingway soundbites is the one I led the post with. Ever read a novel where the author is clearly in love with his/her leading man or lady? Or the one where the protagonist is being handled with veritable kid gloves? There's nothing more annoying than a story with people who don't feel flesh-and-blood real.