In order to determine what is necessary for production, one has to start with the story or the concept that one is trying to immortalize in video, whether it's a fictional film or an online video course.
Scripts are written differently from traditional novels or short stories.
Scripts are less concerned with the internal dialogue of the characters. Instead, the script is designed to illustrate the activities of the characters to reveal their personalities and to guide the story along.
For instance, “Sarah stares at the computer, feeling stressed about her upcoming work.” becomes “Sarah looks at the computer. Her hands shake. Her face has beads of sweat.” The writer must illuminate Sarah’s stress via her physical movements, e.g. the hands shaking.
After the script has been written, one needs to determine how long it will take to shoot everything that has been written and also how much the production will cost.