Cash-back credit card rewards are usually more generous than debit card rewards. And they're also being offered more frequently.

Know that cash-back rewards programs can be complex, says Ken Paterson, director of credit advisory service at research and consulting firm Mercator Advisory Group in Maynard, Mass.

To sort through the noise, focus on the rewards' core earn rates, which are the rewards that you get for each dollar spent, he says. Cash-back cards typically reward you at lower rates, though some bonus rewards like gas may be higher.

Also, some cards have tiered earnings rates; others have flat rates across all categories.

If you opt for cash back, good spending habits are necessary. Cash-back credit cards typically charge higher interest rates than other credit cards, making them pricier if you don't pay on time.