"How to Solve It: A New Aspect of Mathematical Method" by George Pólya provides a detailed and entertaining survey of general methods for problem solving, namely Heuristics. I guess that most people dealing with mathematics in daily life have read this book.
Recently, I came across with "How to Solve It: Modern Heuristics". This book, like its predecessor, is about problem solving, but it focuses on computational methodologies to problem solving. There are many beautiful comments on the book around the Internet. Although its name implies that Pólya's concept of heuristic is traditional and this book introduces a modern one, I think that both are modern in essence and complement each other from a daily practitioner's point of view (I'd name the book as "How to Solve It: Contemporary Heuristics" or "How to Solve It: Computational Heuristics"). Anyways, it will be a lot fun to read it.
I am especially delighted when I read the introductory chapter. Below is a quote from George Bernard Shaw which is given at the beginning of the very first chapter:
The reasonable man adapts himself to the world: the unreasonable one persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man.
-- George Bernard Shaw, Maxims for Revolutionists.
An interesting man, George Bernard Shaw... I like his humour: He is provocative, yet gentle. When I read his views on Islam and the transcript of the meeting of him with Maulana Abdul Aleem Siddiqui, I was so sad about why I was not introduced to his writings before. Maybe, I should have read "How to Solve It: Modern Heuristics" earlier.
Well, it is not too late to read both...