I have thousands of e-books and keep them (mostly) straight with this method:
Audiobooks go in one folder (I have very few, so they're all in folders by book).
Fiction books go in a folder which is subdivided by author. If I've got only one book by a particular author, it goes in a "miscellaneous" books folder. I also have a special folder under Fiction just for fairy tales/fables and one for a set of awards by year.
Nonfiction books (including memoirs and biographies) go under a different folder by subject. I have these main categories (based on the subjects I collect the most of): Computer-related, Cooking & Household, Education & Learning (my children's books end up under a folder there, rather than Fiction), Game-related, History, Humor, Languages (most languages have their own subfolders, and I have a subfolder just for the odd language that I have only one book for), Literature & Writing, Math, Music & Dance, Personality & Psychology, Poetry & Quotes, Reference, Religion, and Science & Health. I also have a Miscellaneous folder which has smaller subsets, such as art, animal care, camping/hiking, genealogy, memoirs/narratives, aviation, survival/prepping, weapons/self-defense, television & media, comics & superheroes, clutter/hoarding, myths & conspiracies, knots, etc. Occasionally I move a folder from Miscellaneous out to the greater folder or to another subfolder (my history, for instance, has quite a few subfolders, for WWII, USA, Britain & Celtic world, Aus/NZ, Middle East, etc.).
Fiction books are always named with author, then title, whereas nonfiction books are always named the opposite, since I am unlikely to remember or care who wrote a nonfiction book. (The few exceptions are usually writers such as Cathy Glass or Casey Watson, foster carers who have written multiple nonfiction books about the children they cared for, and those have special subfolders under the memoirs/narratives folder.)
Audiobooks go in one folder (I have very few, so they're all in folders by book).
Fiction books go in a folder which is subdivided by author. If I've got only one book by a particular author, it goes in a "miscellaneous" books folder. I also have a special folder under Fiction just for fairy tales/fables and one for a set of awards by year.
Nonfiction books (including memoirs and biographies) go under a different folder by subject. I have these main categories (based on the subjects I collect the most of): Computer-related, Cooking & Household, Education & Learning (my children's books end up under a folder there, rather than Fiction), Game-related, History, Humor, Languages (most languages have their own subfolders, and I have a subfolder just for the odd language that I have only one book for), Literature & Writing, Math, Music & Dance, Personality & Psychology, Poetry & Quotes, Reference, Religion, and Science & Health. I also have a Miscellaneous folder which has smaller subsets, such as art, animal care, camping/hiking, genealogy, memoirs/narratives, aviation, survival/prepping, weapons/self-defense, television & media, comics & superheroes, clutter/hoarding, myths & conspiracies, knots, etc. Occasionally I move a folder from Miscellaneous out to the greater folder or to another subfolder (my history, for instance, has quite a few subfolders, for WWII, USA, Britain & Celtic world, Aus/NZ, Middle East, etc.).
Fiction books are always named with author, then title, whereas nonfiction books are always named the opposite, since I am unlikely to remember or care who wrote a nonfiction book. (The few exceptions are usually writers such as Cathy Glass or Casey Watson, foster carers who have written multiple nonfiction books about the children they cared for, and those have special subfolders under the memoirs/narratives folder.)
