This is what we do in Oxford for the Teen Area. We pull out any series of books that has four or more books; if there are only three books, they stay in the regular fiction. Spine labels are author's last name and series name, and we place the number of the book on a round green sticker about the spine label. This works because if an author has more than one series - Melody Carlson, I'm looking at you! - then the individual series stay together, in order. If a series has more than one author - Infinity Ring, for example, we just label those with the series name as author so they're all shelved together. Graphic novels are done the same way, except their number labels are orange. Hope this helps! Feel free to contact me if you have any more questions.

Charli