A credit card for more stable financesWhen you were younger, a low interest credit card might have been the most important factor in choosing a credit card. This makes sense: When you make less money -- as you often will in your 20s -- you're never sure if you'll have enough dollars at the end of the month to pay your credit card balance in full. A lower interest rate helps keep your credit card debt under some control. But how does that change once you've reached the big 3-0 and you're more established in the working world? Hopefully, your salary and your savings have grown. Now you don't worry about paying off your balance in full each month, meaning that a low interest rate is no longer the most important feature of your new credit card. Instead, you might choose to look at the perks which compliment increased disposable income: earn free airline miles, generate high cash-back rewards or provide travel services such as free baggage check-ins on airline flights.