Except for keeping the same author together, I don’t bother arranging my library in any special way.
I prefer to buy actual paper books when I can. Paper mostly because I prefer it, and also because of my preference for physical media; buy rather than borrow because I re-read my books fairly often and also I have this incredible talent for mangling paperbacks.
I do also have an e-reader somewhere, mostly for travel. I get most of my e-books from Standard EBooks and I use Calibre to manage my digital library. There are plugins available for Calibre which remove the DRM from e-books bought off the Kindle store, &c.
Might add some notes on books I like to this page as I (re-)read them. No star rating, assume that anything on this page comes recommended.