Miller tells us a lot about his characters in the stage directions.
Joe Keller is "a heavy man of stolid mind and build, a business man these many years, but with the imprint of the machine-shop worker and boss still upon him" (1.1).
Doctor Jim Bayliss is "a wry, self-controlled man, an easy talker, but with a wisp of sadness that clings even to his self-effacing humor" (1.1).
Chris is "a man capable of immense affection and loyalty" (1.102).
Each character gets an introduction like this on their first entrance. These are early clues to the behavior we can expect from them.
The occupation of each character informs his or her priorities in the play. Joe Keller is a shop worker turned businessman. He's competent but not necessarily wily. His son Chris is a soldier turned businessman, torn between valor and pragmatism. The married women in the play are housewives who exert their power through their husbands, usually in concern for their children. The cynic next door is a doctor; the frivolous, horoscope-reading neighbor makes hats. George, who arrives intending to inflict long-delayed justice, is a lawyer.