Before you select a new credit card, you need to understand your own credit needs and sort through all the fine print. The task is challenging at best, but a mistake can end up costing you a lot. Credit card companies get at least a third of their income from additional fees. Here's some of the things to watch out for.

If You Maintain a Balance

Always look for the card with the lowest fixed interest rate if you are like most people and carry a balance. Stay away with from the cards offering low introductory rates. They can make things really difficult for you if you're unable to pay off your balance before the teaser rate expires. Lenders are also less cooperative to those continually transferring balances to manage their debt.

Find the Best Rate

You can probably find a fixed rate around 10% if you have good credit and your score is at least 720. If you're not so lucky, and your score is more like 650, your best bet will probably be something in the mid teens. You can probably find an introductory offer that's less, but those can have risks.

The Devil's In the Details

Mark on your calendar right away when any introductory offers expire to ensure you manage your funds to pay off your balance on time. Creditors are counting on you to either miss the date or forget about it. Don't even bother if it's only for a few short months. And run the other direction if you suddenly don't qualify for that "pre-approved offer" and suddenly you find yourself in a higher rate category.

Do the math on any balance transfer fees. They usually run in the 3% to 5% range, but they'll cost you even more if you're unable to pay off your balance before the introductory expiration date. They may not be worth the trouble.

Have a Backup Card

You'll find yourself in a bind if you don't have a backup card for all new purchases if you opt for the card with the low teaser rate. When the introductory rate expires, any remaining balances will be charged at the higher rate. Put your new purchases on another card that you pay off each month and you won't find yourself in that bind.

In Closing

You'll no longer be hostage to the balance transfer and fluctuating rate games once you have your balance paid off. But here's one final warning. Don't close accounts or ask for your limit to be lowered, which negatively effects your credit score. To build a better credit score you need to regularly use your cards and pay them off each month. Older accounts hold more merit when calculating your score as does having more available unused credit. This doesn't apply if you don't have your spending under control, but otherwise it's a good thing to keep in mind.