Booking air, hotel or other travel services through your credit card's website may not be the first instinct for most travelers. But doing so can be an especially attractive tactic, according to Goldstein, who says many savvy travelers find excellent deals that are available only to cardholders.

Another option, says Goldstein, is to take advantage of deals offered to cardholders through the airline's website.

"Booking through the airline directly with the airline credit card oftentimes yields double miles," Goldstein says.

To make sure gaining mileage isn't a blow to their pocketbooks, travelers need to do a little more research on travel aggregators, Goldstein says. Once they see the flight on those sites, they'll know if the price listed on the airline's site is the best deal. However, Goldstein adds, to get the double miles, they'll need to go back to the airline's site to book the ticket.