Wash the headlight lenses with car soap and water
Dry the area with a microfiber towel
Tape off the paint around the headlights
Apply toothpaste or a headlight cleaner to the lens
Rub the lens with a microfiber cloth in circular motions
Rinse the lens with clean water
Dry the lens completely
If needed, wet-sand with fine-grit sandpaper
Polish the lens with a plastic polish
Apply a UV sealant or protective coating
Repeat the process on the other headlight