The IBNS Introduction to Banknotes and Banknote Collecting
The International Bank Note Society has published a short but thorough guide aimed at new paper money collectors, and prospective banknote collectors. It is entitled "The IBNS Introduction to Banknotes and Banknote Collecting" and it includes answers and insights to many questions that are and/or should be asked by new collectors. This 36 page document addresses all of the main topics starting with the definition of a banknote, its features and manufacturing process, right on through to types of catalogues, banknote grading, banknote storage information, and a list of equipment a collector should own.
This fantastic and free document is in PDF format and can be found at https://www.theibns.org/intro-to-banknotes/.