It only took my little candy procuring savant one house to nail it: 1)Knock on door; 2) Say trick-or-treat; 3) Say thank you; 4) Say happy Halloween.
Ridiculously cute. If he had to wait behind other kids, he'd be hopping up and down saying "Trick-or-Treat!" the whole time. He also pretty quickly grasped the concept of only going to houses with their porch lights on. "I see lights, Mama, lights! Go dat one!"
Towards the end of our hour-long walk, he was pretty much saying trick-or-treat or happy Halloween to everyone we passed on the street. Dead cute.
Obligatory Halloween photos (Oscar was Max the Bunny; Miles was a pirate):