A great book with lots of recipes. Part 1 is a good introduction and I suggest reading it carefully before trying a recipe because, as the author suggests, you should experiment. If you understand the basics you can experiment with some direction in mind.
I do have a couple of suggestions for things that worked for me when I followed her instructions to try things.
1. Whey: Rather than using yogurt, I drain the whey from near to "best before date" buttermilk through a #2 paper filter and a new plastic filter holder.(ie. no coffee residue) After an hour I get lots of whey.
2. Sourdough: No luck getting a starter until I used "organic" whole wheat flour milled locally.
I was able to come up with these solutions because the author led me to think about the processes.