Outside homie. Clean the headlights with some water and then put some of that plastic x crap on and buff it in with a clean cloth that has abit of abrasivenesses to it (no microfiber) and then once it starts thinning out and drying, buff it with a soft cloth or a microfiber and you will see what happens!
I like the looks of your car, looks kinda like mine

keep it that way haha.