Create a master template of the stage, drawn to scale on a piece of paper. Include the forward edge of the stage, the first rows of audience seating, stage left and right wings and the entire backstage area. One hour of a musical can have anywhere from 50 to 200 blocking diagrams, so make plenty of copies. Mark the sets "U" for upstage, "D" for downstage, "C" for stage center, "L" for stage left and "R" for stage right.
Block the beginning of each act, plotting where actors will be positioned and where the sets will be stationed, then block the start of each scene within the act. These will act as the starting points for the blocking of each scene and will help you organize the diagrams. Dedicate at least one blocking diagram per scene. Mark each character as a circle containing the first letter of their first name. Entrances of actors are marked "ENT," and their exits are marked "EX."
Select a scene and examine where the actors should be at the start of the next scene and which set will be needed. The goal is to manipulate, on paper, how the actors and sets will get from point "A" to point "B." Walking is typically noted with a line of dashes, whereas unplanned, slower movements are typically noted with a dotted line.
Add new blocking diagrams once the page either becomes crowded or when there is a notable or key point of the song or scene. For example, if the chorus of a song has several actors entering stage right in "Scene 1," label the next blocking diagram "Scene 1-A (First Chorus)." Notate the locations of each actor as well as the locations of each set so that the scene is fluid from diagram to diagram.
Compile all of the blockings in sequence from the beginning to the end of the show and be sure that the diagrams flow from one to another. If any movements, choreography or sets are missing, additional blocking diagrams must be added, or valuable time could be wasted in rehearsal.