Outlining Helps You Write Faster
I just finished reading through 2K to 10K: Writing Faster, Writing Better, and Writing More of What You Love by Rachel Aaron. In the beginning she states that by improving the scenes in her outlines she was able to increase the amount of words she writes in a day. I cannot agree more. Even when I write nonfiction, I have a detailed outline of each chapter, what I will cover in each chapter, and notes. Having all this detail in my outlines, I am able to sit down and just begin stringing it all into paragraphs and sentences.
Plot Out Your Book and Avoid Writer's Block
I don't suffer from writer's block, but I believe that is because I always have a list of things I want or need to write. When you create a thorough outline of your book you always know what you are writing about and where your book is heading. You can use the method presented in Karen Wiesner's First Draft in 30 Days and create an extremely detailed outline. You can also learn about the Snowflake Method and build upon that. There are many plotting and outlining methods available. Find one that clicks with you and use it religiously.
Keeps You Focused
It is easy to lose focus when writing a novel of any length. An outline keeps you going. When you look at your outline, you know that your book is already planned out - you've won half the battle. All you need to do is get it written out. Worry about the editing process later.
The Minimum You Should Outline
When writing chapter books for young readers, an outline can be very simple. You can plan out ten chapter or ten scenes with just a brief sentence as to what will happen in each chapter. Short stories can also be plotted with a series of short statements that guide you along your plot. Longer books, such as full-length novels, may need a bit more than a brief statement to move you along the plot and keep you from staring off into nothingness, wasting time dreaming of what to make your character do next.