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.
The novels I love, the ones I remember, the ones I re-read, have an empathetic human quality, or 'emotional truth'. This quality is difficult to fully define, but I always recognise it when I see it: it is different from honesty and more resilient than fact, something that exists not in the kind of fiction that explains but in the kind that shows.