I am often asked what would be a good entry level book into the miniatures wargaming hobby. There are many games that serve as a good intro if someone has already set their mind to a particular period or style but for a great overview I would recommend a book by Neil Thomas called Wargaming: An Introduction (2005). (It can be purchased from Amazon here but always check eBay for a better deal first.)
This is an accessible, straightforward guide to the hobby of miniatures wargaming. It begins with an introduction to the term Wargaming and then includes some notes on how to get started. The layout of most of the book includes trilogies of chapters on six types or periods of wargaming beginning with Ancient Wargaming, with separate chapters for Rules and Armies (army lists). It also looks at Pike and Shot wargaming, Napoleonic wargaming, American Civil War wargaming, Skirmish wargaming (a distinctly different style, such as it is), and then Second World War wargaming, There are a few dozen full-color photos in the center of the book of games in action. If you haven't played and are looking for a complete overview of the hobby, this is a great place to start.