The Beader's Companion (Loveland, CO: Interweave Press, ISBN 1-8883010-56-X) by Judith Durant and Jean Campbell is an indispensable tool for bead jewelry designers at the beginning and intermediate level. It is a small (7 "x 5") paperback book with spiral binding that lies flat, so you can keep it on your work surface next to your beading projects. The pages flip upwards, so that the text is in landscape mode, leaving plenty of space for illustrations.
It is amazing what amount of useful information can be crammed into a mere 104 pages! The book starts out by describing various kinds of beads (with illustrations), as well as types of glass and finishes used for beads. This is followed by section on threads / cords and different types of needles. Particularly useful is a chart telling beaders what thread to use with which kind of bead. There are also extensive chapters on various stitches and crochet techniques (again illustrated with simple, but effective black-and-white drawings).
Further sections on finishings (clasps, hooks, ear wires, etc.), tools and basic wire techniques round out what almost amounts to a beading course in a book. Even after you mastered the different techniques described in this guide, you will be coming back to it for the various useful charts and tips, such as the bead-sizing chart.
Overall, The Beader's Companion is reasonably priced and represents one of the best investments a beginning beader can make. While it cannot substitute for an actual teacher, it offers a good general introduction. Other books and beading magazines will then take you further in teaching special techniques in greater depth.