Reward tiers
Only six cards in our survey have a tiered rewards program. This means you start earning higher payouts when you hit spending thresholds on the card. For instance, Blue Cash from American Express has 1 percent cash back on everyday purchases until you spend $6,500. After that, your rebate jumps to 5 percent cash back. On other purchases, 0.5 percent cash back goes up to 1.5 percent cash back.

According to Curtis Arnold, founder of CardRatings.com, these cards make the most sense for people who spend more than $1,000 per month on a card. Aggressive chargers will hit the highest tier sooner and won't waste as much time earning a standard, or sometimes substandard, cash-back rate. Those who don't charge $1,000 a month might do better with a card offering a flat cash-back percentage.

Tip: Stay within your means and don't overcharge to hit the next tier. Running up high balances can lower your credit score, even if you pay off the balance.

Reward increments
All but six of the cards we surveyed have redemption minimums or reward increments -- that is, you must spend a certain amount on the card before you can get cash back. Typically, you'll see a reward of $25 for every 25 points earned, or $25 for every $2,500 spent. Other cards have higher spending requirements or even tiered increments, with bigger payouts for more points or dollars earned. For example, those with an HSBC American Express with Plus Rewards are required to have 5,000 points to get $25. To get $50, you need 5,000 points, followed by $100 for 10,000 points.

As another example of tiered increments, those with a Chase Flexible Rewards Visa card are required to have 3,500 points for $25, but 10,000 points for $100.

Tip: If a card has a redemption requirement, calculate how much you must spend to see a rebate. Then consider how long it will take you to get that rebate, judging by your spending habits. Use Bankrate's work sheet to keep track of spending requirements.

How often can you redeem?
Some card companies let you redeem as often as you meet the redemption minimum, others are offered monthly or annually.

For instance, you can only redeem rewards from Bank of America's Money Return Platinum Plus Visa credit card annually in January. Rewards earned using a Citi Cash Returns MasterCard, on the other hand, can be redeemed every time the cardholder accrues $50 in rewards.

Tip: This one comes down to personal preference, really. Perhaps you'd like getting some money back each month, or maybe you favor the annual lump sum.

Keep in mind that "issuers always have the ability to change the rate at which points or cash back accrues," says Ken Paterson, director of the credit advisory service at Mercator Advisory Group. "That's always disappointing to the consumer if the payback rate changes at midstream, and that can be a limitation of some of the annual programs."