(Presuming you never, ever carry a credit card balance – interest charges and potential fees will more than consume any side benefit that a card can offer.)

In the old days, the big benefit was airline miles. Let's see how well that works out. The average airfare for a ticket that was paid for with credit card airline miles is about $400. And the average program requires 25,000 to 35,000 miles to be credited a free ticket. Since miles are normally accrued dollar-for-dollar, the average benefit is between 1 to 1.5% of what you spend.

Now we are starting to have something to compare. If you get an offer for a 1% cash back credit card, you'd be slightly better off getting the airline miles. But in my opinion, the many cards offering up to 5% cash back are the best deal, as long the fine print lines up. First, there are normally limitations on the shops where the 5% applies. You want a card that applies the 5% to where you spend the most of your monthly income. The credit card industry calls these ‘everyday purchases', such as groceries, drug stores, and gasoline, but exclude warehouse clubs. You should get a card with the widest number of retailers where you commonly spend money. Or, get a specific-store card for those large one-time purchases. For example, if you are buying new kitchen appliances from Sears, apply and use their card for the purchase and you normally get 10% off. You can cancel it later when it has a zero balance.

The next 5% cash back problem is an annual limit. Citi Dividend credit card limits your annual earning to only $300. If you have some big purchases, you may have spent $5,000 on your credit card in the first month, and you've hit your cash back limit already. So guess what, you are going to stop using that card and start using a different 5% cash back card until you've used up that limit as well. Use them up and move on. American Express currently has a card called Blue Cash for bigger spenders. It offers only 1% cash back until you spend $6,500, and then it pays 5% cash back until you've spent $50,000. But there aren't nearly as many AmEx merchants as Visa/Mastercard merchants. (Again, AmEx and others may have exclusions like purchases at warehouse clubs).

Getting the most from your card is like going into battle: you can have a great plan in the beginning, but once cardholders start exploiting loopholes and creating unintended consequences, the card companies change their policies, it goes back and forth continually. So read all the fine print before applying, and squeeze some extra money from your credit card purchases this year.