For every complex problem there is an answer that is clear, simple, and wrong. - H. L. Mencken
The best how-to guide to creativity may be the one the starts in self restraint.
This video linked from a Fora.tv blog post a week ago, "West Point's most Creative Colonel," begins with a pretty funny punch line built around the following idea: we're inhibited far too often by what we think we know. Have a listen. Then read the quote below linked from the same post.
Another myth [Colonel Casey] Haskins addressed: We know why things happen. 'Why did the stock market go all the way up and all the way down every day last week? The answer is, no one knows,' he said. 'However, I can point you to 25 well-dressed, highly paid people who speak with great authority every afternoon about it.' It turns out we live in a complex world where causes and effects aren’t often clear. Believing that they are 'locks us in to our belief that a particular future is the future, and thereby prevents creativity.'