I've only heard of the wet sand and clear coat method.
Parts Needed:Buffer
Meguiars PlastX
Towels/Rags
1500 or 2000 Grit Sandpaper
Dihydrogen Monoxide
The Process:1) Wet sand the lens in a horizontal pattern until all the clear coat and yellow gunk has come off. Usually takes about 5 minutes per side.

2) Get your buffer and PlastX ready.

3) Put some random dots of PlastX on the lens. Not quite this much, I was being talked to and still had the bottle dripping, lol.

4) Buff for a few minutes.
5) Repeat 3 and 4 if necessary.
6) If you have the lens off of the headlamp assembly (not necessary), Take a rag or towel and rub some PlastX on the inside of the lens.
7) Wipe off any excess PlastX off the lens.


8) If you choose to do so, you can hit the lens with some clear coat. It's not necessary though.
And that's how you do that. No need to be scared!