Start spinning by Maggie Casey (Yarn and bobbin not included)
I learnt to spin by watching Youtube and using the "try it until it works" method. This is good and I am a big fan of the view that as long as you get what you are after then there is no wrong way of spinning (or knitting, or lots of other things provided you stay inside the law ;) ).
That said, I am also a nerd and like to know about different techniques and ways I can improve. This book is great for that. It would also be a fantastic book for anyone just starting to spin to supplement other ways of learning.
Information in here covers the basics of wool, basic drafting, twist, spindles and spindle spinning, wheel details and how to spin on one, plying, finishing, detailed drafting information, using handspun, fleece preparation and wheel maintenance. Loads of information with enough detail to be interesting and useful, but not so much you get bogged down.
The photos are the bit that really gets me excited about this book. They are clear, in colour and show the process being described step by step. A lot of the older books I have read/own have few photos, or black and white pictures that are not always easy to see properly. Spinning is not so easy to describe with words, but a photo makes you go from "huh what?" to "oh, I see!".
I would recommend this to anyone learning to spin, but also to anyone in a similar situation to me, you know how to spin and can make yarn, but don't really know all the details. I wish I had this when I was learning and still feel like it was money well spent.