I have been an author in my own mind for my entire life. I do not know if it is true for everyone but I truly am a living breathing Walter Mitty. When I write my books I have used several methods. I have written outlines with "River Jim" and "Lost Gods" and I have simply followed my characters as they evolve their own stories. This happened in the later process of "Lost Gods", (actually more accurately "The Missing Book of Possibilities"), in "A Moment in Time" and in "Atlas Shrunk" I believe a loose outline is of benefit with the understanding that the characters might have other plans! If you have a dream of writing a book my advice is to begin. Do an outline and get your vision on paper. If you become a successful author or not is secondary. Your book will carry on and somewhere will live forever!