Just making regular transactions without overdrawing the account will begin to build a good record. The next step is to get a credit card. To qualify he'll need to be 18 years old and have either a steady source of income or a savings account. It's easiest to qualify for a department store or gasoline card. If you're a full-time student you won't need to prove your income to qualify for a card with a low credit limit.
Most card issuers are anxious to sign up college students.
Even for major credit cards. Ironically, it's harder to get a first credit card after graduation. The card issuers figure that parents will bail out students but not grads. Margie's son shouldn't apply for a bunch of cards. That will hurt his credit rating.