Show up on time (early) to court. Dress nice- doesn't need to be suit and tie, but show respect for the court. If he can afford it, bring a lawyer. Don't make excuses about being late to something or in a hurry, that doesn't go over well.

Be prepared to be humble and penitent. He can't expect to talk his way out of any punishment, but by being contrite and remorseful, he may be able to mitigate punishment.