i kinda put them in size order (which i guess is really different)..
Because i don't really have a bookshelf i put them in this sort of cupboard thing and there are some in the front and some in the back. My harry potter, twilight series and jodi picoult books go in the front because they're my favourite. I also put my newer books and the books that i want to read in the front. But i go to the library a lot :)