First you gotta prep the lights I wash them with soap and water then I use fingernail polish remover right before i start taping off the reverse lights and also before start painting. It works great on removing any tape residue as well and its cheap as hell.
Second tape off the reverse lights
Then I put something down so I dont get everything black
I then do three coats of the tint
I remove the tape and do one coat over the reverse light and 4th coat on the brake light area
Last I like to do two coats of clear coat
Wait about 24 hrs before putting them back on your truck but it can be 12 hrs depending on the weather. oh and a little tip always wipe the spray nozzle before and after use you dont want sploches.
You can then wet sand them with 2000 grit but personaly I dont do this. The first time I did it didnt turn out great. The second time I let them stay and they shined right up after a couple of months