Les' book is an excellent place to start with testing. Some of us have a disposition towards testing. Ansel's books The Negative and The Print are two places to look if you want to move onward with your testing. Phil Davis' bookBeyond the Zone System is another excellent resource. I would say that this book helped my photography more than any other. As you move onward with testing you'll find that you want a densitometer. The previously mentioned Analyser Pro functions as an acceptable densitometer too. However, my favorite function of the Analyser pro is that it is an f-stop timer.