how do you organize books (physically and digitally)?
Physical books are sorted into categories that make sense and shelved together in logical (to me) order. So for example all science fiction is alphabetical by author then within author alphabetical by series and within series in the order in the universe in which the stories happen not the publication order. My farming books are barns and fences, pastures, hay and forages, nutrition, then genetics then by animal species sheep first then other animals. Sheep books start with general then move to specific, general care followed by lambing for example. Fiber art starts with wool, cotton and flax, fleece characteristics, preparing fibers for spining, then to spinning, nalbinding, sprang, netmaking, knitting, weaving, from warp weighted and belt looms to counterbalance to countermarche to dobby and other types of looms. Then to sewing and clothing, from less tailored to couture.
It's almost impossible to sort e-books into anything useful. I usually read ebooks on my iPad and usually kindle format so I'm tied to the Amazon approved sorting and categorizing methods.
So for all book types I have a full inventory in BookPedia. I'm slowly putting what bookcase and what shelf each book belongs on into the database to aid in finding a specific book or more importantly, putting it back whnen I am done using it.