Heres a quick guide if you want to smoke exterior lights.
Materials: VHT Nite-shade ( Advance Auto )
High Gloss Laquer Clear ( Lowes )
2000 Grit Sandpaper
Painters tape
Take off lights, prep by cleaning with a degreaser, and then soap and water, dry really good. tape off all areas, lightly sand with the 2000 just to have a surface to bond.
Put as many coats as you would like to get the shade you want. let dry. wet sand lightly with the 2000 grit, clean, and dry. then put a nice medium to heavy coat of laquer
high gloss clear, one or two is all it takes, this will make them glossy just like the paint on your car, and will be a good protective clear coat.
Before:
After: