All you have to do, you're told, is apply for the store's credit card right on the spot. What should you do; save some money or pass on the offer?

There are several things you need to consider. Are you going to be carrying a balance on that card? If so, check the interest rate.

"Often the interest rates and the finance charges you're going to end up paying would far outweigh any discount that's being offered," explains Andrea Rock, a senior editor at Consumer Reports Many retail cards have a very high interest rate, Rock says, significantly higher than bank-issued credit cards.

According to Bankrate.com, the interest rate on the average fixed-rate credit card issued by a bank stands at 13.03 percent this week. The average bank-issued fixed-rate Gold card is now 11.38 percent. Many store cards now charge 21 to 24 percent interest on unpaid balances.

If you want a store card, see if the retailer offers what's called a "co-branded" Visa or MasterCard. It's a store card that's also a Visa or MasterCard, so you can use it outside the store; anywhere Visa or MasterCard are accepted. Consumer Reports says co-branded cards tend to have lower interest rates than a store-only card and they also tend to have better perks.

Getting one new credit card that saves you a bundle on a large purchase might make sense, just don't do it at store after store. "The trick is being savvy about choosing and using store cards," Consumer Reports advises, "and not going for every offer." Apply for too many new cards in a short period of time and you'll do more than weigh down your wallet, you could hurt your credit score. Consumer Reports says every time a company checks your credit report (which happens when you apply for a new credit card), that inquiry can lower your score by 5 to 40 points.

If you score drops enough, you could find it harder to get a loan or see the interest rate on your other cards jacked up. Why? "Because they've decided you present a greater credit risk because you now have more available credit," Rock says.

For more information:

Store credit cards: flashy perks, high rates