He only makes a little income. Can he get a credit card that will allow him to earn miles?
The best solution is None, until he graduates and starts making enough to pay the nasty thing off every month. It's SO easy to get into debt with credit cards!!! And it's Horrible to try to climb back out.
If Mom and Dad are into helping him, they might do a reloadable credit card and let him use it like a debit card. Once the balance is gone, it's gone, though.
Have him try this: Make out a monthly budget. Go ahead and put in a certain amount for credit cards, and allow for some "toys" or whatever in a separate part of the budget. Figure the average amount he'd be paying a credit card company every month. Look around and find a credit union close by. Credit unions offer savings accounts to members with an average of $5 to keep it open. Take the amount he'd be spending on credit cards and deposit that into the savings account every month, and watch how fast it grows. Use the budgeted "toys" amount for his "whatevers."
Then if he wants to spend money from his savings, he can. But if he's smart, he'll let it build and then every so often transfer a thousand into a short-term CD. If you watch the rates, the short-terms are just about the same APR as the long-term. He can time it just so, and they'll mature in time to pay on tuition and books for whatever semester is starting.
Also, he'll develop good credit with them, and credit unions are great places to finance homes, cars, and so on.
I give this advice to all my young clients: "You gotta feed your wallet. If you feed your wallet, it'll feed you."