Read whatever you can get your hands on. It’ll make you a better creative, whether you’re a writer, art director, designer, UX guru, creative technologist, whatever. But don’t limit yourself to “ad books.” Learn to communicate in ways that aren’t covered in the Advertising sub-shelves of the Business section at Barnes & Noble.
Pick up a copy of Anne Lamott’s Bird by Bird. A beautiful and inspiring piece. I don’t want to call it a how-to. But it will help you how-to: communicate, question, wonder, ponder, reconsider, and get to work.