Read the script several times and take careful notes pertaining to the setting -- time, place and weather. Review the need for furnishings -- for example, does the actor sit on a sofa, a chair or a rock?The story line will dictate the need for props. For example, does the actress take her coat out of the closet or off a coat rack?.
Meet with the director, lighting director, sound designer and costumer to discuss the vision of the play, any limitations and details so the play has a unified look.
Create a sketch of the set based on the meeting.
Measure the area of the stage and draw the area to scale on the graph paper. You can use a four block per square-foot ratio.
Draw a floor plan for each scene using an above view of the set and clearly positioning scenery and furnishings.
Draw the front view of the set, which shows details like elevations, platforms and windows, for each scene.
Create colored sketches for each scene. The color and details should correspond with the director's vision for the play.
Transfer the two dimensional drawings into a 3D model either using a computer drafting program like AutoCad, or creating a model with cardboard and small figurines. This helps to visualize how the actors will interact with the set.