The picture must tell the story. Forget every other rule, and you will still be ahead of the game. Try this trick. Watch your commercial with the sound turned off. Here's another test.
Most good commercials can use one single frame for a brochure or poster that tells the whole story.
Grab the viewer's attention. The first 5 seconds of a commercial are crucial. Analysis of audience reaction show either a sharp drop or a sharp rise in interest during this time. Be single minded. A good commercial is uncomplicated, direct.