This may surprise you, but I have a few knitting books.
If you only buy one knitting technique book EVER, make it Nancie Wiseman's Knitters Book of Finishing Techniques. This book walks through a manageable number of cast-ons, bind-offs, increases, decreases, seams, button bands, and other finishing techniques. She explains the pros and cons of each, which increase/cast on matches which decrease/bind off, and when to use a particular technique. The illustrations are fanastic in that they show, for example, exactly what an SSK decrease is supposed to look like as well as exactly how to do one.
I find The Knitter's Book of Finishing Techniques waaaaay more helpful than Montse Stanley's Knitter's Handbook : A Comprehensive Guide to the Principles and Techniques of Handknitting. The Knitter's Handbook contains 1-2 sentence descriptions of each technique, sometimes including a very vague drawing. While the Knitter's Handbook includes many more techniques (over 30 ways to cast on!) the depth is overwhelming for someone who wants a useful resource for quick questions. I usually can't make heads or tails of the instructions and eventually turn to Nancie Wiseman's book.