Sabrina Karl knows how to take control of a credit card and use it to her advantage.

For the last five years, Sabrina, 36, and her husband have charged as many household and personal expenses as possible on their United Mileage Plus Platinum credit card to earn rewards in the form of airline miles.

The credit card, offered by Chase, gives one mile on United Airlines for each $1 spent on purchases as well as special bonuses.

"We charge every single thing we can on this one card," she says. Groceries, eating out, local and long distance phone services, along with charitable donations, internet service, gas -- even the water softener bill -- are all charged on the card, the only credit card she has.

"I never have more than $20 in my wallet at a time because I so rarely use cash," notes Sabrina. "In fact, I use my credit card for so many things that I often go a week or two with just five or six bucks in my wallet."

The miles they've earned have allowed Sabrina and her husband to fly free from their home in Madison, Wisc., to vacations in New Mexico and the Canadian Rockies, and they're planning a trip to either Central America or the Caribbean later this year.

When her grandmother passed away last fall, Sabrina booked her younger brother a ticket to Calgary using miles from her stash so he could attend the funeral.

With such short notice given the circumstances, the airfare would have been almost $800, which my brother would have found almost impossible to afford," she explains.

Sabrina investigated various rewards cards before choosing the United Mileage Plus card and has since considered switching to a card that gives miles useable on any airline. However, she opted to maintain status quo.

United offers a plethora of flights from her airport, she's been satisfied with the card's terms and she can pay the $60 annual fee with miles, "essentially making the card completely free."

She offers these tips for how to make the most of your rewards card:

• Make it a habit to ask every place you spend money whether they accept credit cards. "More places than you think will accept them," Sabrina says. Case in point: She recently learned that she could buy bus passes for her daily commute online with a credit card at the city of Madison's ePayment Center, as well as pay for many city services, such as water. Unfortunately, property taxes are not among those payable by credit card. "Too bad, because that would be a nice chunk of miles!" she says.
• Keep spending within your limits. Sabrina learned her lesson with credit cards early. She always carried a balance during college and graduate school but felt sick each month when she received her statements and saw those finance charges. She paid off the last of those cards while engaged. Now she and her husband have an aversion to any debt, with the exception of their mortgage, and only charge what they know they can afford to pay off each month. "There's no use in getting free miles if you're turning around and paying finance charges on a revolving balance," she says.
• Find out which restaurants by you offer special bonus miles when you pay for your meal with your mileage card. Such promotions will give you double or triple miles for your purchase, according to Sabrina.
• Plan ahead for trips using earned airline miles to avoid difficulty booking your flight. "We're getting better at making our plans further in advance and last time, we got exactly the flights we wanted," she says.

By Darci Smith

Interest.com Contributing Editor

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