The Seven Secrets of How to Think Like a Rocket Scientist by Jim Longuski, is one of the books that have enjoyed the most.
The book is not a text book with theory and equations, (the What), in rocket science; but rather the presents in an organized way approaches and methods, (the How), that rocket scientists follow to approach the challenges of their endeavour. Despite the title, the book is written in an elegant but simple English that aims for the general public. In the same sense that knowing how the most acclaimed chefs prepared their dishes can improve anyone's cooking; anyone's skills to solve problems in the daily life can be improved by applying some of the methods presented in the book.
The book has a section for each of the seven secrets (Dream, Judge, Ask, Check, Simplify, Optimize and Do); and each section is divided in brief chapters that present a concrete concept / methods, which is very often accompanied by anecdotes that make crystal clear the importance of such method. Among the ones that I use / remember the most is the KISS (Keep It Simple, Stupid) principle.
As the cherry on the cake, at the end of the book, the author provides a distilled list of related reading material, as well as sci-fi.
P.S. Be aware that the author makes very clear his position towards the space shuttle program.