Where there is nothing, there is nothing to organize.
The library is created long after the book. One may build bookcases with the intent to fill them, but the labels will be wrong and the shelves will have too little headroom. Eventually, the perverse urge to find books that fit the shelves will come.
Buy a book first and read it.
A single book is already organized.
After reading the book and finding it valuable enough to keep, simply keep it. Who knows how big or small the next book will be, or what language it will be in, or what it will be about? Any free corner is an adequate place to leave a single finished book.
Buy another book.
When there are a few, distinctions finally become apparent.
Finished books may sit underneath new books; An ordering is effortlessly established. Books may be found with only a glance at the spines. Similarities and differences may become apparent between the books, yet there is still no need for more than a simple stacking of the books.
Buy more books.
Patterns emerge from examples.
When it becomes difficult to pull the desired book from the stack, only then is it finally time to start thinking about a shelf. How many and how to arrange the books is obvious now that they are here. If it were another set of books then perhaps they would be arranged another way.
Grouping similar books on each shelf is adequate. Alphabetical ordering or other total orderings are unnecessary: A dozen books can be scanned rapidly as long as the appropriate shelf can be found.
Group your books and build shelves to suit them.
Books are for reading.
If you spend more time arranging your books than opening them, then you have too many books. They are a burden rather than a resource.
Ruthlessly rid yourself of the books you don’t read.