I have used the Mothers head light restoration kit, it works amazing. I'm sure most of the name brand kits will work great.
Just make sure and follow the directions. Tape the painted area around your headlights to avoid getting the compound on the paint. It is abrasive and will scratch. I used painters tape.
Yeah, the 3M units work great. I've done about 4 or 5 sets of headlights with the kit. Takes about 20 minutes if you're comfortable.
Like everyone else has said, done more then I’d like to say using the 3m kit. Take your time and make sure the finish for each level is consistent before moving to the next.
Did my headlights with the turtle wax kit (power drill wet sand kit) and as long as you follow the directions and use sealer they stay looking great for a long time. I agree with everyone else though, a name brand kit preferably one with sanding pads or power drill pads because I found those to work better than the pumice gel type fluid you just apply and scrub.