Book to read and reread. Describes the obvious and rather good things to know.
However, this book is a bit over rated. You will surely galérer to find your marks at the beginning and especially
finding the right program / software / application that you can apply this methodology daily.
Things I use the app on Mac OS X personally, once understood the principles, it remains for you to customize the method
GTD to your tastes and personality. Very hard to follow at first. And especially to maintain, and this for a while.