The Office of Open Records website (which, by the way, is scheduled to get a much-improved look and feel tomorrow!) includes numerous guides about the Right-to-Know Law for both requesters and agencies.
The newest — and most comprehensive — of these is our new Agency Open Records Officer Guidebook (PDF).
The AORO Guidebook, 79 pages in total (with a variety of sample forms agencies can use as templates), is designed to provide a general overview of the RTKL process from an agency perspective. We tried to write it to be helpful for both new and veteran AOROs.