The book I would recommend is called Eats, Shoots and Leaves by Lynne Truss. I love this book since it makes me laugh in its approach to explaining punctuation. There are even really cute stickers which the book calls a "punctuation repair kit" included for those who wish to use them. I personally enjoy the history behind the different kinds of punctuation and how to use them. The main reason I love this book so much is I enjoy English and language in general, this book puts plenty of humor into learning the rules of a part of the language.