Based on my experience as both performer and acting coach, I'd strongly recommend that aspiring, and even seasoned Thespians research and read every book they find on the subject of theatre--both its historical and current movements--whether it's specific to acting or not. For stage diction, in particular, I'd suggest Cicely Berry's "Voice and the Actor."
Robert, this is a great recommendation—continuing to study both the history and technique of the craft can really deepen an actor’s understanding and versatility. For members looking to grow, combining resources like these with practical application through Stage 32 labs and opportunities can be incredibly valuable, and we’re always here to support and guide you!
Since graduate school, I've studied acting with Word Baker at Cincinnati Playhouse in the Park, Stuart Culpepper at Atlanta's Peachtree Walk Theater Company, Gene Frankel & Leonard Melfi and Rodger Hendricks Simon in NYC. For anyone interested, I now coach privately at a reasonable rate.
Theater history was one of the most boring classes I ever took. I don't think you need to study Kabuki theater to be a good actor. I do agree that diction in theater and learning standard stage speech is important.