Frederick James Crowest defines his book, 'Advice to Singers', as not a guide on how to sing, but rather a collection of hints for aspiring singers. He emphasizes the importance of having a teacher and dispels the myth that singing can be learned from a book alone. Crowest covers a wide range of topics, including habits, pronunciation, voices, instruction, practice, style, expression, time, and music selection. He stresses the need for a good education, discipline, and perseverance in the study of singing, as it is an art that will test one's character.