Just a couple of things to think on when planning your script.
It is generally agreed to be the max length that people will watch, before switching off.
Work on the fact that you need to get your most important message in early to capture those that switch off early
Work on a max 150 words per minute in the script.
Keep your message as succinct as possible: “never using two words when one will do”
Use active verb tenses.
The shorter you can get your script while still saying the same thing, the more value each word will have
Be economic with the words, drop the adjectives and adverbs.
“Paul walked briskly down the leafy lane toward his holiday home, looking forward to the warm winter fire” great for a novel, but for a script, “Paul walked Home” is much better.
Know your target audience
Call to action
Choose a mode of persuasion as a theme:
Ethos. Appeal to the viewer based on your credibility
Pathos. Appeal to the emotions of the viewer
Logos. Appeal to your viewer’s sense of reason