The Design Institute for Physical Properties (DIPPR) maintains the DIPPR 801 database for the American Institute of Chemical Engineers. The 801 database is the largest collection of critically evaluated, pure-species, thermophysical property data in the world and is used by engineers and academics. This paper is a response to misuse of the DIPPR 801 database in the literature. To help researchers avoid misuse, the critical evaluation process for property values is explained, and common mistakes that occur in the literature are outlined. A guide to using the DIPPR database for both academic and industrial use is also included.