I apologize for the delay in responding, and thank you for posting. A 30-second commercial script is often written in a two-column format: video on the left, audio on the right. A simple skeleton is: hook (0-3 seconds), problem or setup, the product or message as the solution, and a call to action at the end.
With 30 seconds, you have about 60-75 words of voiceover, so every line counts. Our Screenwriting forum is a great place to share drafts.