Cash advances
By taking out cash advances that you can’t pay back right away, you’ve got the wrong idea about credit cards. You get hit double with cash advances, with APRs commonly up to 26%, plus the fee when you take the cash out. And not only does your credit card company typically charge a fee, but the ATM or bank that processes it for you charges, too.
Cash advances are really just a loan against your credit card. If you need the cash and can only find it on your plastic, think about other unsecured loans—bank loans will almost always carry a lower interest rate.