Do nothing — absolutely nothing — on your novel in terms of actual writing until your plotting (along with your characters and their roles in the drama) is complete and down on paper.
     Do not fall victim to that old author line: “I just start out with a basic idea and a couple of characters. I never know where I’m going. I let the characters tell the story for me.” That may work for brilliant and experienced novelists, but most of us need a clear road map if we aren’t going to get ourselves and our readers hopelessly lost.