I wonder how many people know that they can use Word's Outline View to create a sophisticated outline.
I used it when I wrote Get Your Writing Fighting Fit. I did begin on paper because I wasn't at my computer, but as soon as I could, I started an outline in Word.
I could move whole sections simply by dragging the heading.
If you haven't tried Outline View yet, head up to the menu bar when Word is open and give it a try.