Outline simply. Do this by sketching down on paper the general contents of each chapter of your novel. Write down the general flow of the plot and action. Don't get bogged down in the details at this point. You may want to jot down important aspects of your characters at this point as well.
Write down ideas as they come to you in any order during the writing process. As your novel progresses, discard the ideas that don't seem to fit. In this method, getting your ideas down on paper might help you remember the good ones as you get going with the novel.
Write a detailed outline. Some writers find it helpful to get every detail down in an outline before they write the first word of a novel or book. You may use headings for each chapter with subheadings showing how the action will progress in the chapter. In order to do this, you must already know how the book will work out in advance as if you've already written the novel in your head.