Here's a list of a few things that you can do to make sure that you take full advantage of your credit cards and to prevent them from taking advantage of you.

Don't Just Assume—Call And Ask

If you get hit with a late-fees or some other penalty, just call in and odds are that the card issuer will be happy to waive the fee(s) in return for a satisfied customer (as long as you don't make a habit of fee-accrual of course). Is your interest rate/APR too high? Call in and see if they can lower it for you. Credit limit too low? Call them up and request an increase, or do it through your online account center (don't bother trying until you've had the card for at least a year though). Did a new card come out that has a better rewards program? They can usually switch your account over to that card with no penalties, no credit pull, and no hassle. They can usually even move your current balance over to the new card!

They won't do this stuff for you automatically—you have to call in and request it. If they aren't receptive to your requests you can always ask to cancel the account—this will often prompt the customer representative to be more receptive to your requests.

Minimize Number of Cards, Maximize Your Credit

Have extra cards that you ever use? Don't cancel them and hurt your credit score by reducing your total amount of credit and wiping out each of the card's individual histories. If you have multiple credit cards from the same issuer you can call them up and have them roll your credit line into one card for you. That way your history is also transferred into the new card. This is great for those who take advantage of 0% APR offers (since you usually only have these cards for one year or so just to take advantage of the introductory balance transfer option).

This is also a good option for those who take advantage of the introductory mile bonuses on frequent-flier/mile program credit cards. You can cancel the card at the end of your fee-free introductory first year and downgrade to a yearly fee-free version of the same card (although mileage rewards are usually reduced in half from 1:1 to 2:1, dollars to miles). One example is the Citi Bronze AAdvantage World MasterCard.

Traveling Overseas? Use Capital One and Discover

Most credit cards charge a fee for converting currency overseas…even if the store you're at charges you in U.S. dollars (or whatever your home currency is)! This fee is usually around 3% of the transaction, which can really add up over time.The way around this is to use a Capital One card or a Discover card, since they do not charge these extra fees. I would advise against making the Discover card your primary card though, as it is not widely accepted throughout the world.

See the post Using Credit Cards Overseas for more information.

Read Up On Your Card Benefits

Have you ever taken the time to read that long brochure with the small type that you receive with every new card? Most people don't, and they miss out on potential benefits by not doing so. Little things like credit card car rental liability insurance, or the fact that most credit cards double the manufacturer's warranty on items that you buy (American Express adds two years onto the standard manufacturer's warranty!). Or how about vacation insurance, or roadside assistance? Every card provides different benefits, many of which are not expressly stated. Read up.