Again, sometimes the simplest way to do something is to NOT reinvent the wheel. You can use the Dewey Decimal System to organize and classify your nonfiction books, and it works very well for that purpose. Read more about using Mr. Dewey’s system of classification here (Part 1), and here (Part 2), and here (Part 3). Dewey is not that hard to learn, and it arranges your books into subject categories for you so that you can move on to actually reading the books instead of spending your time organizing and classifying them.
However, some of us like inventing and reinventing, or we want to do things just a little differently from the way Melvil Dewey shelved his books. SO here a few other possible organizational schemes.
Sandy Hall of Hall’s Living Library:
Here’s my list of categories. Basically, it follows the DD system, just by category rather than numbers. Then I alphabetize the books by the author’s last name within each category. I might have added a couple more since I typed up this list.