Uh... chunks? I suppose academic/studies books are in their own area & ordered by title, unless they're oversized & need to be put elsewhere. As we don't want our fantasy novels mixing with our religious studies books when we need those, lol. Fantasy & that general genre are then sorted by title, barring oddities. Art books only go with art books in a seperate area, as all of them tend to be oversized & tall or too long. I guess whatever can fit whatever. We have such a huge variety of books that a lot of it currently is hugely disorganized & shelves are sagging under the weight. I never sort by author because my memory is poor & we rarely have anything by the same author, or like- I don't want Vyasa (Mahābhārata) to be at the end of the shelf if I sorted by author? Dunno we're a mess due to my partner & I mixing academic books with stuff like Battletech novels. Alphabetical is about the best we can get.
I don't get people who organize their books by color... I mean it looks pretty, yes, but how do you ever find the book you want? Maybe they've only got non-serial books, so then it doesn't matter?
Definitely by series, but the actual order outside of that is more aesthetic and what I think is going to be used the soonest. I have a few indie graphic novels like that, it's really amazing how good some of the spines look for them
I only organize books by general category. I have fiction books in one pile and nonfiction in another and then sort those books by genre for fiction and subject type (politics, economics, biography, etc.) for nonfiction.
I have them organized in a way that I understand and can easily use, but it would take a very long essay to explain why, which is how I organize most things to the chagrin of basically anybody that asks.
Like, I have a collection of over 800 blu-ray and DVD titles and they are organized in a more complex way than I think anybody who shares the hobby would ever, but if you ask me to find one I will pretty much be able to find it instantly depending on how recently I've added new stuff.