This guide is designed to provide educators with basic information on both the proper utilization of the overhead projector and the preparation of good visual materials. Focusing on the mechanical aspects, the first section briefly outlines how to handle problems with the projector lamp, and provides information on general maintenance, proper projector positioning, and how to conduct a trial run. In the second section, instructions for using the screen emphasize proper placement to avoid image distortion, and two diagrams illustrate best and poor screen-projector arrangements. The third section discusses types and preparation of transparencies, including the use of markers and professional artists; transparency lettering and layout; legibility; and storage. Concerned with the actual presentation, the final section suggests techniques for: (1) focusing student attention in the proper place; (2) using acetates and overlays effectively; (3) soliciting student involvement; and (4) controlling both the visual materials and the audience. The guide is illustrated throughout, and an eight-item bibliography is provided. Both English and French versions of this guide are included in this document. (DJR)