(Take an example, which should be a relatively politically neutral topic with a long shelf-life).
Your voice-over for templates 1 and 2 will have three tight, well-constructed sentences.
1. Where it is and what is happening / who is doing it. THE HEADER
2. Background or more information. THE EXPLANATION
3. What will happen next or what viewers can do. THE FUTURE
Then sign off with your name and organisation. THE SIGN-OFF
Make your sentences sound like attention-grabbing headlines, not a school essay.
Look for the unusual, or even the unique ("break-dancing grannies", the "man bites dog" principle).
Be well-informed and accurate. Add something the viewer doesn't know and can't just see in the pictures.
Go for a bit of poetry in your phrasing.
Story about the demo against your local swimming pool being closed down.
1. Temple Cowley swimming pool, Oxford, where enraged residents are picketing against the closure of this vital local facility.