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 How to Solve It: Modern Heuristics. This book, like its predecessor, is about problem solving, but it focuses on computational methodologies for problem solving. There are many beautiful comments on the book around the Internet.
I was 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.
George Bernard Shaw is an interesting man. 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 sad that I had not been introduced to his writings earlier.