In this video Justin explains the language of the stage and some of the important considerations when presenting a stage show. He explains the terminology.
Stage left, stage right, upstage and downstage. Find the centre stage and mark it off. Do this in agreement with the lighting department. A compromised centre must be found. He demonstrates a good example of an asymmetrical room, that is, the centre of the room is not the centre of the stage. It is important to consider where the singer may be standing and marking it off to define exactly how to orientate the stage equipment. Access to the stage needs to be clear and a clear view of the stage for technicians. It is equally important to be able to access essential items like mains distros, fire extinguishers and the like for health and safety reasons.