Finishing, joining, and generally doing things really well in knitting can be challenge. I still have to look up "mattress stitch" when I really need to do it.
Tips for Knitters, by Debbie Bliss, delivers on the basics (like mattress stitch) and offers up some more elaborate techniques, too.
The book seems to have been designed to slip right into a knitting bag. It's less than 8 inches tall and bound with a spiral binding that's covered with a paperback spine. This means you can open the book and it will lie flat, but there is no exposed spiral to snag on your yarn.
Photographs of Debbie Bliss patterns appear throughout the book, but it is absolutely a technique book. There is not a single pattern included.
Bliss covers yarns, equipment, understanding patterns, beginning to knit, stitches, increasing and decreasing, fixing mistakes, color knitting, seams, finishing touches, and care of garments.
This is all information that you could get from other sources, but it's rare to find all of it together, explained so clearly.
Some techniques I think are covered especially well in this book are slip knots, cable cast on, different forms of yarn overs and knitting with two strands of yarn. It's all in a very relaxing, friendly tone of writing, too.
"Try to make sure that you are feeling fairly calm - anxiety is bound to make your knitting tighter!" is just about the best bit of advice I've seen about stranded knitting (page 128).
Overall, a lovely little book that would be great for a beginner but a boon to the veteran knitter, as well.