Watch your credit card rewards pile up with these 5 tips

Just because summer's approaching doesn't mean your wallet gets a vacation. From graduation and wedding season to Father's Day to the Fourth of July and other vacation plans to 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 some "stacking" strategies for your credit card.

Check your account for offers

Some 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 are specific to your card. Chase Offers and AmEx Offers, for example, are visible to eligible cardholders when logged in. They feature discounts or bonus rewards at dozens of retailers, including many brick-and-mortar merchants, although you must opt in by "adding" the offer to your card.

Sign up for retailer email lists

Ever had a salesperson offer you a discount on the spot if you sign up for the store's credit card? Similarly, when you're shopping online, many stores will offer you a percentage off your first order if you sign up for an email list, so snag that discount on top of your normal credit card rewards.

Maybe it's free shipping you want. Seventy-five percent of consumers now expect it even on orders below $50, according to a report by the National Retail Federation. Signing up to receive a retailer's emails can be one way to get free shipping, at least on your first purchase. (Note that retailers charge different prices for shipping and may not add that cost to your total until it's in your cart.)

Another way to dodge shipping charges: Buy online, preferably through an online bonus mall, and pick up in store. This may also require you to submit your email address and be added to a mailing list. But agreeing to receive correspondence from a retailer is much easier than signing up for a store card. If those emails start getting overwhelming, just unsubscribe.

Buy discounted gift cards

Gift cards remain popular: 45 percent of respondents in NRF's 2019 Mother's Day Spending Survey said they were planning to purchase them.

Buy them at a place where you already earn elevated rewards for shopping. For example, if you have a card that pays high rewards on supermarket purchases, pick up a gift card for your favorite retailer while you're getting those groceries. You'll earn the same high rewards as you would on your milk, eggs and bread.