I have taught Advanced Placement writing for over 13 years and have been a writer for over 25 years. I can tell you that one of the most important skills a writer can develop is an ability to outline.
First of all, I want to make sure that the reader understands the difference between outlining and brainstorming. Brainstorming is where we create a myriad of ideas based on a topic in order to formulate other ideas and hopefully some original ideas. Outlining is the activity by which a writer takes those ideas that they developed in brainstorming sessions and organizes them into a coherent structure.
I usually outline the plot of my novel first, with each roman numeral representing an individual chapter. I insert any ideas I have as I go, but this helps me to structure the novel so that all plots and sub-plots are covered and followed to their logical conclusions. I can say from experience that even if you are a writer who places your main character into some type of conflict (whether internal or external) and then allows your imagination to get them out of it without a formal outline, I would argue that you still have some type of rudimentary plan in the back of your mind as to where you want that character to end up. Why not go the extra mile and plan that out on paper so that you can go back and edit it, rework it, before writing fifteen chapters that you have to scrap because you don’t like them or they don’t end up “working”.
The mind is an incredible thing, but if you are like me, remembering all the major plot points and symbolism and other devices can get overwhelming. If you don’t outline, you may end up with a more shallow rendering of your vision. Why not record the plot and sub-plots so that you can see the entire text at once? This will allow you to go through it numerous times and tweak it until it is put together more like a fine tapestry rather than a cardboard box.
I have outlined my current novel project. I have a general plot line, but having it written out allows me to see the bigger picture. It has helped me to insert more detail, more allegory, more symbolism and more of the stuff that makes a novel worth reading and worth thinking about.
If you are someone who has fought writing outlines, then give it a try just once. I promise it will be worth the effort. For my AP students, it is often the difference between scoring a 2 (capable of college work) and a 5 (eligible for college credit).
Writing Is Hard Work 
This is why I love using Scrivener! I’ve previously been more of a pantser/basic outliner but, having clear separate chapters with each having a post-it style synopsis section means that I can work out what’s happening better. I can quickly see an overview of what has happened previously and I can then work out what’s to come next, how to get there, who’s involved… When looking at the corkboard page with the post-its on, you can also work out at a glance what’s missing. (Shouldn’t she have been in there? How did they move to there? Doesn’t that need exploring?) You can add extra chapters so easily in between. There’s also a research folder and you can add other folders for characters, settings, etc.
It sounds like I’m on commission, doesn’t it?
Really, all I’m saying is. I’m finally developing a more structured approach to my writing. Whilst I won’t plan the shit out of it before I start, I can easily go through and pad out, explain, shift, move, edit and so forth, as I go along if I need to. My plans are flexible but effective so far.
Kelly.
I’ve commercially published two non-fiction books — and every book proposal requires a lot of thought and planning, from a TOC to chapter titles and descriptions. I tell would-be authors it’s the blueprint. You have no idea what sort of structure you’re going to build until this is clear. No agent, editor or publisher will take you on without one.