I have mine semi-arranged by genre and semi-arranged by space. And occasionally by author, if they write mostly the same type of novel.
Vampire books take up about a shelf and a half, then it's on to Harry Potter and other magical things.Then fairies, demons, futuristic-type books, sci-fi, "chick lit", and what I refer to as "problem books"--things like
Running With Scissors and
Fight Club and books about eating disorders and mental issues.
On my second bookshelf, I have all of those "rich kids at private school" books like Kate Brian's
Private series and
Gossip Girl and all that. Then there's "Brit chick lit", like the Georgia Nicholson series and the
Mates, Dates series. From there it segues into historical books, books I've had to read for school, a bunch of
Fruits Basket volumes, and other random books that don't belong anywhere else. And then there's the non-fiction and self-help books, followed by things I read when I was younger.
And I have the
Series of Unfortunate Events books and assorted DVDs shoved in randomly wherever there's space.