I highly recommend that every Pagan, Wiccan and Heathen have their own private library.
Books I highly recommend for a good understanding for your private library of the history, philosophy, practices of the modern Wicca and Pagan religion.
Isaac Bonewits- Bonewits's Essential guide to Witchcraft and Wicca
Isaac Bonewits- Real Magic
Margot Adler- Drawing Down the Moon
Starhawk-The Spiral Dance
Starhawk-The Earth Path
Michael York- Pagan Theology
T. Thorn Coyle- Evolutionary Witchcraft
Ronald Hutton- Triumph of the Moon
Robin Wood- When, Why...If
Topics that should be represented for expanded world view. Each of these have a special value in creating the larger picture of thought and practice. There are more ways to go with each of these subjects that whatever your preference you can find ones that fit your vision, yet still give you more information then you had before.
World Religions, World mythology, Psychology, Anthropology, Optical Illusions, Labyrinths, Cooking, Gardening, Sustainable Living, History, Rites of Passage, Logic, Art, Music, Theatre, Divination, Physics, History of Science, Alternative Architecture,
Then you should have at least 4 books on whatever tradition you are most interested in. Over half those books should be on the traditional culture that its about, with the smaller part being modern practice.
Celtic/Druid, Norse/Teutonic/Heathen, Wicca (If you're claiming Wicca you better be familiar with Gerald Gardner), Hellenic, Egyptian, etc. I'm a believer that the re-creationists library should have about 95% scholarly texts regarding their tradition. If you're going to recreate the ancient practices you need to know all you can about the culture, philosophy, religious practices, political history and interaction with other cultures that you can to fully understand their mind set.
While this is often viewed as an anything goes sort of way to do things, it shouldn't be. Usually there will be some defining feature that links the various parts of your path. That can be about anything from the garden to cooking to philosophy to healing to science to anthropology to meditation to a focus on one tradition with add ins from other traditions in an attempt to enhance the basis. Total whatever goes is really chaos magic/spirituality. Which has its place in the grand scheme of things as well, though I suppose its to much to ask the chaos folks to admit their chaos... perhaps that isn't chaotic enough of me?