From Consumer Reports magazine, here are three tips for how to use credit cards that offer rewards so you benefit:

Run the numbers. Before choosing a card, estimate your spending and translate that into how much cash back or points you’ll earn through the program. Once you have that number in mind, find out how many points you’ll need to qualify for something you want. If your spending doesn’t get you anywhere close, it’s best to forget about that card.

Think twice about rewards if you carry a balance. Rewards credit cards often charge relatively high interest rates.

Use your miles. If you’ve racked up frequent flier rewards, use them. Cashing them in has become more difficult as airlines cut flights.

Marketwatch