Here are some random thoughts, some of my reference points regarding scenography. They may seem a bit conventional, so I will hasten to mention that in the past I have done exciting experiments where, for instance, the scenography was the central “actor” in the production. What is usually needed though is for the scenography to function as a kind of “story-telling machine.”
A very good book that explains these “machines” is Richard Southern's “The Seven Ages of Theatre.” It presents a cyclical, multi-cultural history of theatre, as determined by the evolution of the playing space and the relationship between audience and performer. The chalk circle, the Elizabethan thrust stage, the commedia dell' arte booth stage and the proscenium arch are all very specifically designed machines for telling stories.
I am more interested in the design of the three dimensional space than, for instance, decoration, texture, or promoting clever concepts. I am less interested in scenography that represents literal spaces such as kitchens, courtrooms or bedrooms. When necessary, it is enough to just suggest these spaces with simple elements backed up by the conviction of the actors. What is more interesting is to create dramatic space, historic space, erotic space, martial space, or absurd space; a space in which the actor is inspired to use voice and body to assert influence, expand situations, develop metaphors and tell stories.
It is important that the audience is an active participant in the creation of the illusion. If you try to fool them, then you risk insulting their intelligence. The audience needs to feel confident that the actors know that they, the audience, can still tell the difference between what is real and what is illusion, and that they have willingly suspended their disbelief. A wooden sword is more theatrical than a metal one because it is so obviously not real and begs of the audience a more active and imaginative participation.
I like a scenography to present physical challenges to the actors. Having to work with it and against it provokes the actor into being more physically expressive. It should open up possibilities for building visual metaphors for the dramatic relationships. So it helps if there are different qualities built into the space, that there are places in the scenography where the actor is exposed (and it might be something just as simple as being able to stand on a bench) or concealed, or protected, or commanding, or off balance.
Comedy and tragedy make different demands on the design of the space. Horizontal lines are funnier and emphasize the vertical movements of the actor that are typical of comedy. Vertical lines in the scenography suggest grandeur, and emphasize the horizontal movements of tragedy. Melodrama, or tragic-comedy as it is sometimes called, is all about diagonals.
For comedy, each member of the audience must have the same experience at the same time or they won't synchronize their laughter with each other. There should be only one focus point on the stage at a time, and the audience's attention must be continuously directed towards it. Where the acting style involves sight gags and “takes” to the audience, you pretty much have to seat the audience close together in one area. Curved seating, as opposed to straight rows of seats, gives a more generous feeling and encourages laughter. Because of the importance of pace, rhythm and surprise to comedy, places for entrances and exits (doors, windows etc.) need to be close to the action on the stage.
Scenographers often forget the importance of the stage floor. The floor not only provides support and framing to the stage picture, it connects the actor to the audience through the ground, rather like the way in which an old fashioned radio used to have an earth connection as well as its antenna. If the stage floor is noisy, the actors can't ignore it, they have to use it as a musical instrument. I have seen a production of a Shakespearean comedy with the stage covered with a thick layer of sand. It looked great. Unfortunately, it took all the spring and precision out of the actors' movement. Although the idea didn't work for comedy, it might have been quite brilliant for tragedy, where the actors could have trailed their feet through the sand.
Most importantly, a scenography should be an incomplete work of art, demanding that it be completed by the action of the play.