As a general rule, 150 words is good for a minute-long video. You can try your script by reading it aloud at a comfortable pace. If you go beyond this number of words in a minute, you’d be running out of breath. When you experience this, start trimming the piece so it won’t end up becoming a business nightmare.
After editing, go through the same process. Repeat it until you reach the level when reading is already comfortable and almost effortless.
Another thing you have to keep in mind when writing a script is the value of breaking things down into smaller pieces. This means that if you’re looking at an online video that’s 4 to 6-minute long, you should divide it into two or three discreet parts that will give viewers the leeway to navigate in between. This will not only benefit them, but you too, as it will give you more flexibility in shooting and editing.
Speaking of the shooting and editing, another aspect you must focus on when writing is the on-screen elements and actions that will go with the entire script. Is there a need for on-screen graphics? Are you going to use on-screen texts? These details and others must all be included. To do this, it is then crucial to have a good picture of the already-completed video in your head. It will save you a lot of time, money, and effort in the long run.
Finally, after writing a script, never forget to do a dry run. Before setting up the location and bringing in the crew, you would want to make sure that everything is as flawless as can be. The flow, the pace, the details of the onscreen elements— they should all be ready to work together and create a video that tells a good story.