You need to study and plan ahead to let the credit cards work for you, but believe me, it will be a worthwhile effort. If you reap less than $100 a year from credit card rewards, studying these tips from CNN Money for an hour can at least double your rewards for the next 12 months.

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Point-based programs aren't such a great value, either, since items in reward catalogs are usually way overpriced, according to Curtis Arnold of CardRatings.com. "If you spend $10,000, you'll get 10,000 points. But in the end, if you're only getting a toaster oven, you're getting shafted," he says.

Yes, it's all in the details. With cash-back cards, you may have to spend a certain amount annually before you get the advertised rebate. In some cases, that can be over $6,500 a year. And beware of caps! There may be a limit to how much you can get back. In some instances, you may be limited to $300 a year.

You also need to get the details when it comes to redeeming your points. Cards may give you a timeline to cash in points. And sometimes you'll have to pick up the phone and call the company to get your rebate check.

Also, don't forget that issuers can change their policy at any time to increase fees or limit rewards with only 15 days' notice.