The supreme quality for leadership is unquestionably integrity. Without it, no real success is possible, no matter whether it is on a section gang, a football field, in an army, or in an office.
I tend to get comfortable with the dialogue and find out who the person is in the script and try to hit that. People are sort of independent of their occupations and their pastimes. You don't play a politician or a fireman or a cowboy - you just play a person.