You can use an abrasive tooth paste and a polishing ball if you want to. Here is what I have learned after several months of doing head light restoration at our shop. We use 3M at work, but you have to remember to use the UV protectant or the lights will fade again quickly.
I did the lights on my truck with the 3M and an air powered orbital polisher.
It really doesn't matter what type of compound you use as long as you realize you will be removing some of the plastic material and you need to remove as little as possible and protect it from the UV rays.
Some abrasive compounds are harsher than others, so read the labels.
Mel