Tonkin, Stephen: Binocular Astronomy, 2nd Edition
It would seem odd not to recommend my own book!
The first edition of this title was praised for its suggested objects for observation and especially for the finder charts for each object. In this second edition, this section is expanded in three ways. There are new objects, more information on each object, and a re-organization of the objects for binoculars for easier selection.
Binocular Astronomy 2nd Edition puts an emphasis on understanding binoculars and their use. The additional content reflects the latest developments in technology, new testing techniques, and practical ideas for binocular use. It also responds to the substantially positive reviews of the first edition, and is now even better suited to its target readership.
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.