Paying with plastic is rarely a rewarding endeavor these days, even when a card offers bonus points, miles or other perks.

Not only are card issuers jacking up interest rates, but the reward programs now come with plenty of strings attached -- such as hard-to-get application bonuses, lower earnings capability or inflated prices for rewards.

But for all the hoops to jump through, rewards cards can still be profitable. Here are ways to get the most out of them:

Opt for a cash-back card. Changes to your rewards program, like the percentage you'll earn, will be more apparent with this sort of card. And cash-back programs carry low administrative costs -- the issuer doesn't need to manage a redemption site or cut in airline and retail partners -- so major adjustments are less likely, says Curtis Arnold of CardRatings.com , a credit-card comparison site.

Seek instant gratification. Be cautious about investing in a program that requires months of building up points before you can claim rewards, says Samir Kothari of Billshrink.com , an online program that helps consumers compare credit-card deals. The longer you must save, the greater the risk the program will change in some way that devalues your earnings -- or will cease to operate altogether.

Assess your spending. Most cards offer reward bonuses for spending in certain categories, either as a regular feature or a temporary promotion. Choose a card that lines up bonuses in categories where you spend the most, advises Jenn Stoddard of Utah-based Family First Federal Credit Union. When shopping online, link to favorite retailers through the card's rewards mall to earn extra rebates.

Skip the stuff. Redeeming points or miles for merchandise is often the worst way to spend rewards. With Bank of America's program, for example, it takes 25,400 points for a blue 8GB iPod Nano. For 25,000 points, you could get $250 cash, enough to buy the player at Apple.com for $149, with $101 and 400 points left over.

Check retail partnerships. Redeeming rewards for gift cards can be among some of the best deals, says Mr. Arnold. Discover offers bonuses on its cash-back cards for taking gift cards from affiliated companies such as Border's (get a $25 gift card instead of $20 cash) and Kohl's ($45 instead of $40).