After seeing a few threads of fellow members referbing their headlights I thought I'd give it a go. My car is a 2002 vectra so its had 8 years of road rash on the lights. It also seemed to have some sort of greeen mold that I could never wash off.
I useed wet n' dry 800 grit first, then went to 1200, then 1500 and then finally 2000. I do have 2500 grit but didnt feel the need to go that far.
I then used 3M Perfect-it III™ Fast Cut + Compound for a super smooth finish. Then a polish with MEGUIARS PLASTX.