Some tips from my experience:
1. If you're going to wash your car the same day as you restore the lenses, wash after you do the lenses. Some plastic dust blows around and there is some spatter on the wet sand.
2. Be sure to really protect the surrounding paint. 3M recommends two layers of automotive masking tape, which I did. But I did cut through in two places with the edge of the sandpaper. So if there is any chance of touching the body of you car with the edge of the sandpaper, put on 3 or 4 layers of tape.
3. The kit comes with plenty of supplies: sandpaper and plastic polish. The directions warn that there may not be enough supplies, but I had plenty left over, although admittedly the Jetta headlights aren't that large. I don't see any...