For people younger than 21, getting a credit card got harder with the CARD Act, which requires applicants an adult co-signer or proof of income for applicants between ages 18 and 20. That narrows the pool of available cards significantly. American Express and Capital One don't allow co-signers, and any card not specifically marketed to people with limited credit could saddle a young, inexperienced applicant with interest rates approaching 25%.

Even cards specifically for students can be risky. The law doesn't prohibit lenders from counting student loans and other financial aid as income. That could inflate the offered credit line beyond what a student could reasonably repay, and continue the cycle of debt that the new laws aimed to halt.

The best student credit cards offer some incentives and tools to teach users how to approach credit wisely, and a rate of no more than 20%. "I like the cards that try to set good habits early on," Harzog says. Citi Forward for College Students offers the same pay-on-time rewards and interest rate reductions as the adult card (see "For managing debt") and an APR of 12.99% to 21.99%, while Citi mtvU Platinum Select Visa Card for College Students awards points for maintaining a good GPA, paying on time and sticking to your credit limit. Its APR ranges from 12.99% to 20.99%. Both allow -- but do not require -- a co-signer. (Go with the co-signer if you want a rate on the lower end of that spectrum.)

Journey Student Rewards from Capital One has a rate on the higher end at 19.8%, because students must apply on their own, but offers texted payment alerts, 1% cash back and an extra 25% bonus on cash-back rewards earned each month when you pay on time. (A Capital One spokeswoman says it has the added benefit of a fixed credit limit cardholders can't exceed.)