Hi, i painted from the outside :a: , you basicaly need to isolate the part that comes to be the clear after painted, (reverse+blinker) with any kind of good tape, after 2 or 3 coats of the (apple red, clear testors) you're done, you can apply a clear coat but is up to you :naughty: , after a year of something you may need to paint again, but after 1 yearand 2 months my tail lights still look good, way better that the orange stock ones and WWWWWWWWAAAAAAAYYYY better than altezzas!
I hope this was helpful! and send me a pic!!

Oscar