I have just done my rear lights, i used 800 wet and dry paper in warm soapy water, then 1200 grit in soapy water then 1500 grit in soapy water, then a finishing or polishing compound, then buffed them up with auto glym super resin polish :)
Worked great and removed my old laquer and tint, and the scratches that i had gathered over the years
Tom