Well, first of all, you read the script a million times. Because what the script gives you are given circumstances. Given circumstances are all the facts of your character.
“Tires were so bald on the truck that the air was showin' through, and I had to drive fifty miles an hour all the way out there, because the vibration was so bad.”
“As the treaty made with the United States was the first treaty entered into by your country with other countries, therefore the President regards Japan with peculiar friendliness.”