Sometimes less is more. Simple set designs can help highlight the plot of the play. This works well if you are working with a limited budget. You can show the emotions of the play and the characters with a single piece of furniture, some simple black or white curtains and some lighting. To help convey isolation, black curtains can be used in the background. The lighting can be limited to a spotlight on the character as he sits at a kitchen table.
Lighting is an art form. You can use one light source to simulate sun or moonlight. This single source should light the entire stage. Point source lighting can be used when you want to highlight a character. This will make the character and the character's immediate surroundings stand out. If the stage is separated into different acting areas, use the McCandless Method, named for a pioneer of modern lighting design in America.
Risers and platforms help break the monotony of one stage floor. Risers work excellently for a chorus or possibly to split focus on purpose. An elevated platform, likewise, may focus attention on a character giving a speech.
Simultaneous and multiple settings occur on one stage. The difference is that simultaneous settings happen in one area of the stage and are frequently set aside with lighting. For example, you can set different furniture sets in different areas of the stage and use different colors in that area. When the characters are in one area, such as a kitchen, highlight it with lights and darken the other areas of the stage.
Multiple settings are clearly separated from one another. You can do this by building a wall between the two environments. You can build an upstairs section of a house, with bedroom furniture and stairs leading up to it from the downstairs. This is more expensive. You can also represent two completely separate locations on each side of the wall. For example, you can show an office setting on one side and on the other side, construct a tavern setting.