I'm a big fan of Patents Demystified as a guide to patents for inventors and startups. Some folks here on Stack Exchange suggested it to me and it was just what I was looking for. Seems like the patent book that most people use.
It has a great foundation of the basics and works up to intermediate and advanced patent strategies. Unlike most patent books I found, this one is really easy to understand and has specific actionable steps and strategies for protecting inventions and maximizing protection.
It's primarily directed to the U.S. patent process, but also discusses how the foreign patent process works as well.