Just because summer's approaching doesn't mean your wallet gets a vacation. From graduation season and Father's Day to the Fourth of July and back-to-school spending, you'll likely drop some dollars. Rewards-earning credit cards can help you save on these expenses - but you can also combine those rewards with other money-saving strategies to help you hang on to even more of your cash. Here are five such "stacking" strategies for your credit card.1. CHECK YOUR ACCOUNT FOR OFFERSSome card issuers have online bonus malls - accessible via account login - that offer discounts or higher rewards rates at hundreds of merchants, on top of what your card already earns."I recently bought new outdoor furniture and a gas firepit, and I logged into Chase, clicked through the portal to Lowe's, and got an extra 3 points per dollar spent," says Holly Johnson, founder of Club Thrifty , a personal finance blog dedicated to saving money.You can also check for one-time or limited-time promotions that … [Read more...] about Watch your credit card rewards pile up with these 5 tips