Treat them like a debit card and you'll be okay. :)
Actually, they're a good tool for establishing credit when you're young, to rent cars and buy things on-line, and for use in emergencies, etc. I use mine for the additional warranty and I treat them like a debit card. I pay the full balance each month; no finance charges or annual fee. If you use it like this, the interest rate is not an issue because you never pay finance charges.
If you have to carry a balance, then you want the lowest rate possible, a reasonable grace period (unlike my cards which give me 10-14 days because they know I always pay the balance in full each month), and a low annual fee, if any.
If you treat it like an extension of your checking account, you'll do fine.