Seconded. Some of it feels a bit dated, and it doesn't cover tools you can use like PowerMock if your codebase is Java and you really just need to get a piece of hairy code under coverage as quick as you can without having to refactor it all to be testable the 'normal' or 'clean' way. Nor does it cover refactoring for a functional and immutable approach (its approach is much more OO). Still a great resource to have on hand and be inspired by.

The most important thing is to follow its advice and just start doing it little by little, even small refactors of other people's code. A friend's company had a Book Club and some testing book got on the list at one point, and as they were discussing it they kept having arguments over how effective various things were, so they resolved the arguments by starting a Testing Club where every week everyone would put in at least an hour into getting some part of the system under test, or trying out a testing technique, and discussing it. Over time they got most of the product under test and fixed a lot of previously unknown bugs.