Unless you have an annual fee there won't be any charges on your account if you pay your balance in full every month.

An APR is your annual interest rate. It is, however, slightly different than the interest stated. The difference is due to how the interest is calculated. Ie. your interest is often charged on the "average monthly balance" vs. "the balance of the last day". Thus, if you recompute the interest rate, you'd have a slightly different rate than the regular interest rate. However, I've found that most credit cards state their rates as an APR.

I don't know about a low APR rate, but a low credit card rate would be at or below 10%, I think. I know that many years ago there were cards with 3 or 4 percent rates, but I don't think they are around anymore. My lowest rate is 11% and it is with a credit union I have a checking and savings account with.

If you have an annual fee or transaction fees, those will be in addition to your interest. An annual fee usually comes with a card that has a fantastic reward program and/or a very low interest rate. OR, in case of people with bad credit, the only way to get a credit card. Transaction fees are usually charged if you draw cash from your credit card and/or overdraft, make a purchase in a foreign currency and/or transfer a balance.

Another factor to consider is any reward programs. American Express has some great cards where you get points based on your spending and you can redeem them on many ways - giftcards to just about anything and flyer miles, etc. Make sure you have use for whatever reward you might get - if you don't care about frequent flyer miles (like me as I dont' want to be bound to those terms when I do travel), you may want to look for a cash reward card and/or one that offers gift cards to starbucks, department stores or restaurants you frequent. Discover has a cash back program.