Tonkin, Stephen: Binocular Astronomy
It would seem odd not to recommend my own book! From the publisher's blurb:
Ridpath, Ian and Tirion, Wil: Collins Gem: Stars
This little "gem" is often overlooked by serious astronomers, but its small format (8cm x 11.5cm) gives you a star atlas in your shirt pocket! Separate chart for each constellation, down to mag 5. Lots of DSOs, including the Messiers, are marked.
Consolmagno, Guy & Davis, Dan: Turn Left at Orion
The new edition of this excellent book, packed with viewing tips and clear instruction. Also realistic drawings of what you can expect to actually see.