In a readable and accessible style, John Shook provides an excellent introduction to the "A3" plan for problem solving. It is the most accessible and understandable beginners level book I have seen on the subject.
Pascal Dennis' "Getting the Right Things Done" also covers the A3 process - though for strategy deployment. Personally I find John Shook's "Managing to Learn" more readable and a better introduction to the A3, though they do cover different ground and the one doesn't replace the other.
If you want to know more about the A3 planning and problem solving process - that ties everything in lean together - this is a great place to start.