My dad once told me that writers write. As a professional writer, I would add that writers also read. Whenever I begin a new writing project, the first step always involves reading -- and lots of it. At the moment, I'm writing a book on leadership and performance improvement for a new client. It's aimed at a general audience, so I'm reading a bunch of titles that would normally be off my radar. For instance, I'm reading "The Purpose Driven Life" by Rick Warren because it's divided into many short chapters and people seem to like that kind of approach. I'm also reading "Strengths Finder 2.0" by Tom Rath, which is a popular self-help book. And I've picked up a copy of "Secrets of the Millionaire Mind" by T. Harv Eker, to see how he integrates the book's message with his training business.
For ideas and inspiration, I'm reading "The Power of Myth" by Joseph Campbell, "The Rational Optimist" by Matt Ridley, "Nonzero" by Robert Wright, "Drive" by Daniel Pink and "Predictably Irrational" by Dan Arielly. These are exceptional books, and I recommend them highly.
For me, one of the best parts about starting a new writing project is that it gives me an excuse to go out and buy a new bunch of books. I need to see that stack of books sitting on my desk ... that's how I know I've got to start writing again!