Advice, written as a set of instructions for a private collector and was based on Naudé's own experience and research. In the introduction of his book, Naudé wrote that he is not an expert in the field of librarianship but he presented what he believed to be the most important ideas. He based some of the opinions in Advice on his own experience in Mesme's library, and wrote out for Mesme the accepted practices and principles of librarians of the time. Chapters covered topics such as number of books, selecting the books, procuring the books, etc.
Naudé's first chapter poses the question, "Why establish a library?" He answers the question with a simple message; there is no greater honor than building a great library and sharing it with the public. Naudé believes libraries should model themselves after the best libraries of the world. The first task is to create a plan. Before a person can erect a library, he must educate himself on the subject of collecting and organizing books. A person must also seek the guidance of those who have already built their own libraries or are in the process. He suggests studying and copying the catalogues of other libraries.
Naudé devotes an entire chapter to book selection, remarked upon throughout. The first authors who need to be purchased are those considered experts in their respective fields. No matter whether they are ancient or modern works, if a book is held in high regard by practitioners of a particular field then it should be present in any collection. In addition, any well known interpretations or commentaries that exist are a necessity. Naudé suggested purchasing books in the original languages because meaning can often be lost in translation. He is strongly against censorship of any kind. Naudé believes that every book has a reader regardless of the subject; and that information should be free and available. Readers could always find use of a book, even if it is to refute the ideas presented on its pages. Certain books are popular at times but later forgotten; he argued that it would be beneficial to a library if there were multiple copies of these books to accommodate the popular tastes of the times.
In his chapter on book acquisition, Naudé gave tips. The easiest way is to purchase another library in its entirety. Naudé went on to praise second-hand book sellers who often provided good books at cheap prices. Naudé himself browsed book-binding and printing shops for used paper, and had once discovered a rare manuscript that a book binder was using as scrap paper.
Naudé included a chapter in Advice for arranging the books. In discussing arrangement he quoted Cicero, "It is order that gives light to memory." He gave instructions that he considered logical. His subject headings included: theology, philosophy, jurisprudence, medicine, history, mathematics and humanities. Naudé would add other subject heading in later years but these categories best represented the known body of knowledge in the world. Each section should be divided into subheadings and begin with the principal authors followed by the commentaries.