As the user of a word processor, you have access to the program's Outline feature, which you may find useful. It's often found on the View or Tools menu. Once you become familiar with it, the outliner can help you establish and arrange complex organizational categories and subcategories.
Still, a note of caution is in order. Until you get used to the outliner, you may find that it's interfering rather than helping. Don't try it for the first time when you're working against a deadline. Experiment with it, and if you think you'd like to use the outliner in your writing, read the documentation to learn more about its features.
2.9 Create a short outline of your own using your word processor's Outline feature. Include at least seven items and three levels.