If you play your cards right, small everyday purchases put on plastic can add up to big savings over time.

That's thanks to increasingly generous credit card cash-back rewards programs — provided you pay your bills promptly — according to one credit-card comparison website. In addition, the right card for you likely depends on where and how you live.

Those are among the findings of a recent CreditCards.com analysis of U.S. Bureau of Labor Statistics data on typical consumer spending in several large U.S. cities. The website then tried to recommend the best card matches for local residents.

"Whatever you spend your money on, that's how you should pick your credit cards," said Ted Rossman, industry analyst at CreditCards.com. "It was really interesting … how much spending varies by metro area."

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New Yorkers, for example, spend 121% of the national average annually on public transportation, whether in cash or by credit or debit. (They also, unsurprisingly, spend 28.21% less at the gas pump.)

The Big Apple is rolling out a new contactless transit payment system dubbed "OMNY" that doesn't just make it easier for commuters to fork over their $2.75 fares; it could also potentially earn them credit card rewards points every time they wave their smartphone or contactless card over a subway turnstile sensor.

To maximize rewards, CreditCards.com recommends New Yorkers consider cards which offer the most cash back on transit such as taxis, ride-share services, parking, tolls, buses, trains and more. Other public transit-reliant cities where commuters could benefit from a similar card include San Diego, San Francisco and Washington, D.C.

Los Angelenos, meanwhile, tend to drive more, spending $2,706 a year on gas — 28.31% above the national average. A good fit for them might be a card which offers 3% cash back on fuel, among other perks.

Transit, in fact, is on the rise as a rewards-generating category of spending, "especially as cities like New York and Chicago get deeper into contactless cards and being able to tap and go on the subway," Rossman said.

Gasoline purchases, streaming service subscriptions and food bought both for home and at restaurants are also types of habitual spending that might be better put on a card.

"As long as you're paying your bills in full each month and avoiding interest, I would suggest putting all the money you would have spent anyway on a credit card because it really does add up," Rossman said. "I earned almost $2,500 in cash back last year and almost all of that was from regular spending."

However, if you normally carry a monthly balance, it's best you forget about cash back or travel perks. "It doesn't make sense to pay 17%, 20%, 25% just to get 1%, 2% or 3% cash back," he said.

Cash back rewards are, in fact, cardholders' preferred loyalty perk, according to CreditCards.com. A recent study found that about two-thirds of cardholders choose cash over travel rewards like airline upgrades.