I have all poetry in one place, all Latin & classics stuff in another (not in perfect order), all children's books in another room (a favorite topic), all bios & autobios together (except for what's with classics), general history stuff all together(ditto), spiritual stuff and whatever I'm currently reading on a bookshelf next to my bed. Adult fiction alpha by author, and everything else on one large bookshelf, pretty much in sections (Shakespeare & drama, foreign languages, dictionaries & reference books, etc.) When I was first confronted with this (when I was first divorced & living alone) I went to the library and got a handout on the categories in the Dewey decimal system, and used that to give me an idea of categories. If I had just done fiction/nonfiction, I would have had too much of a mish-mash. The basic set-up I did years ago has worked pretty well. Have fun! It's a luxury to be able to do this.