Joan Frey Boytim has had a distinguished career as a private voice teacher. Rather than a manual of how to teach singing, this handbook covers more of the logistical concerns about teaching voice -- where and how to establish a studio, how to teach voice students sight reading, how to establish a curriculum approach, organize recitals, and other concerns.
Most voice teachers will find this type of manual valuable. This is because while most voice majors study the ins and outs of the instrument and pedagogical approaches, very little focus is placed in education on how to organize one's teaching ability into an effective vocation. Boytim's suggestions, while simple at times, can be quite helpful. For instance, when first building a studio, Boytim suggests one teach beginning piano (or any other instrument teachers play) as well as voice in order to fill a studio. Non-voice students can be phased out of the studio as the number of voice students grows.
Boytim also provides an immensely helpful method of teaching sight-singing quickly and relatively effectively. Her literature recommendations are also very sound for young singers. Some of the volumes Boytim recommends have been compiled, of course, by herself, but I highly doubt she's in it for the money. I've used one of her books for baritones and found it to contain many songs which were both entertaining and of musical substance.
Critics may note that Boytim doesn't see much value in taking on students who aren't there to learn and who are "just there to hear themselves sing." While philosophical differences between teaching styles are common, I think voice teachers with a divergent view can easily read those passages with a grain of salt and move on to the more helpful sections. Boytim does have a significant section on figuring out how to comply with U.S. tax law, so voice teachers outside of the 50 states may find the book less helpful.
For the voice teacher within the United States, however, this book has the potential to be an enormous resource. I strongly recommend it.