It depends what area of the craft your interested in...
Like for me I'm wiccan so I would ultimately refer a begginner to get these three books first if possible:
Raymond Bucklands: Complete book of witchcraft
Scott Cunninghams: Wicca a guide for the solitary practitioner
Denise Zimmermann and Katherine A. Gleason: The complete idiot's guide wicca and witchcraft
Obviously not all witches are wiccan, so even if you don't choose wicca as a pagan path those books will give you a slew of knowledge to start a definate strong foundation for the craft..
Raymond Buckland's book is like a text book filled with lots of knowledge, quizs after each chapter to see if you've retained what you've read, rituals,spells, practical magick, meditation,herbs knowledge,etc.. it basically will give you a definate start with a power punch into the craft. Scott cunningham's book is really easy to understand and he breaks it down for all to grasp it well it also includes easy solitary sabbats and esbat ritual, practical magickal practices, exercises,etc.. It'll also get you on your witchy feet and on your way, and the last book; The idiot's guide, doesn't mean your an idiot it just breaks down what it means to be a witch, and the diffrence between being just a witch or a wiccan or other path that goe's hand and hand with being a witch, it has spells,rituals,history, correspondants, all the basic knowledge needed and much more... Even if you don't get the other two books this book will get you up and kicking in no time also its a useful book to have on any witches shelf to refer back to as a note book if one doesn't want to go back through their slew of collected witch books over time..
Obviously theres many more books and like I said before it depends on the practitioner what variety of the craft they get into just make sure you get your strong foundation first...Those will do it for ya..
I hope you find all you need and that you have a blessed and light filled path