I've always been the pedantic sort that strictly adheres to the time-tested method of organising books alphabetically by author; going...
I've always been the pedantic sort that strictly adheres to the time-tested method of organising books alphabetically by author; going so far as to separate fiction and non-fiction, then reserving a spare shelf (or several) for "yet to be read" books. That was when I had the pleasure of sprawling my collection across several large bookcases, having the luxury of a miniature (yet ever-growing) library at my fingertips. Since moving I've had to downsize my collection considerably (weep) resulting in a mere two modest bookcases to shelve the remaining favourites.
While my vintage book collection is organised by height, housed above a small collection of graphic novels (also organised by height requirements), in a separate room, hidden from prying eyes (and fingertips); the rest of the collection has been organised by colour.. for no other reason than it looks rather lovely. I might never find any book I want to read ever again since adopting this pretty yet haphazard organisation system (not so much now but definitely when my collection begins to grow again), but at least the shelves make for a colourful addition to our living space.
Other ways to organise your books:
1. Alphabetically by Author (the most sensible option, of course)
2. By size
3. By topic, genre, or type
4. By the status (read/unread) or frequency of use
5. In gigantic piles, everywhere; stacked all over the place