Kroger is one of the largest retailers in the world, second only to Walmart here in the U.S. So chances are, you've been to a Kroger at some point, especially if you have gone grocery shopping in the Midwest. In addition to operating stores under the Kroger brand, the Cincinnati-based chain has 24 store affiliate brands, including City Market, Dillons, Fred Meyer, Harris Teeter, King Scoopers, Ralphs and Smith's. Overall, the company is in 35 states. With such a wide footprint, Kroger offers a lot of promotions and programs to help you save money on your everyday groceries and essentials. And while it can be a challenge to keep track of them all, it's definitely worth opting into a few of the biggest money-savers. Here are eight common mistakes grocery experts say you should avoid if you're looking to maximize your savings during your next Kroger shopping trip.

1. You're not part of the Kroger Plus Shopper's program

The old adage is true at Kroger: It pays to be a member. And the best part is, it's free and takes just a few minutes to sign up. Kroger's membership program offers shoppers digital coupons and personalized deals, as well as access to fuel rewards (more on that below). You can definitely shop without a Plus card, but the digital membership and coupons are pretty convenient. Even more so if you download the Kroger app (which is also free!). Then everything lives on the app, so you only need to bring your phone with you in order to save money when you shop. "Kroger is one of the best supermarkets to coupon at," Joanie Demer, co-founder of the Krazy Coupon Lady tells CNBC Make It. But even if you don't like to coupon or do a lot of advanced planning, the Plus card is worth it. Simply open the Kroger app right before checkout and see if you can take advantage of any deals.

2. You don't shop the Mega sales

Kroger, like most traditional grocery stores, has a lot of sales. But shopping experts say there is one that shoppers shouldn't miss: Mega sales (also called "Cart Busters" or "Mix & Match" at some locations). "Their Mega sales are fantastic, so whenever they have one, taking advantage of that is a huge saver," Laurie Hise, founder of the Passionate Penny Pincher site, tells CNBC Make It. "Just get on their sale cycle and follow it." The Mega Sale is a regular store promo that happens at least once a month. The details vary, but many times it's set up as a "Buy 5, Save $5" sale. If you purchase five participating items you'll save $5 at the checkout. For example, this week's Mix & Match sale for a Cincinnati-based Kroger includes Jif peanut butter, Keebler Town House or Club crackers, Land O'Frost premium turkey and black forest ham lunch meat and Dave's Killer organic breads. "It's more important to shop Kroger around sales," Demer says. "Their sales are going to beat Walmart every time." Hise says she recommends shoppers take reusable shopping bags with them to the store and group sale items together in them to ensure that you're buying the right amount.

3. You never take advantage of the Friday freebies

That's right, Kroger has free stuff for its shoppers. Almost every Friday, the chain rolls out a digital offer for a freebie. But you don't need to rush into a store every Friday. The Krazy Coupon Lady site notes that the offer is available to download on Fridays, but you can cash it in for your freebie for up to two weeks. So far this year, the site reports freebies have included things like Butterfinger candy bars, Sweetarts Chewy Cherry Punch Rope, Simple Truth ready-to-drink coffee and a Neuro drink.

4. You've never used Kroger Pickup

Formerly known as ClickList, this is Kroger's pickup service that can really save some time and money because you don't even need to get out of the car to shop. You can order all your groceries ahead of time through the Kroger app or website, select a pick-up slot, and a Kroger employee will meet your car in the parking lot and load your groceries. "It's a money-saver for moms who are busy and don't have time to go in, especially if you've got little ones," Hise says. Through the service, the first three pickups are free. After that, Kroger frequently runs deals if you buy a specific product or set of items, the pickup is free. "Nobody's grocery pickup program is better than Kroger," Demer adds. You can reserve a pickup time up to three days in advance, although the Krazy Coupon Lady site notes that peak times are weekdays between 4:00 p.m. and 7:00 p.m. Keep in mind that if you are planning on using coupons, it might be best to avoid Wednesdays, since that's when Kroger changes up their weekly ads, the site reports. So your estimated price when you check out may look different than your total if you purchased items that were on sale in the previous weekly ad. But you can use both digital and paper coupons when you go to pay for your groceries with Kroger pickup, so "you can save money from the parking lot," Demer says.

5. You buy all your organic foods at Kroger

Both Demer and Hise say that organic food prices at Kroger are a bit high. You're better off shopping at Aldi or Trader Joe's if either chain has an outpost near you. That said, Kroger's meat quality and prices, both organic and traditional cuts, is worth a trip into the store. "The meat is a really good value. Their meat sales actually beat the Aldi and Walmart prices consistently," Hise says.

6. You buy your flowers from Kroger

If you're looking for a bouquet to grace your dinner table, skip Kroger. "Flowers are always a bad deal," Hise says. The food site The Kitchn did a price comparison between Aldi, Costco, Kroger, Trader Joe's and Whole Foods on the flower bouquets offered. Kroger ranked among the most expensive of three of the four bouquet options the Kitchn evaluated, including a dozen roses.

7. You've never stopped in the clearance section

Kroger has great clearance areas scattered throughout the store, including on produce, which Demer says is rare among grocery chains. For example, her local Fred Meyer packages $5 mixed bags of fruit that is ripe and should be eaten right away. At Demer's Fred Meyer, red "WooHoo" and yellow price labels are used to indicate sale items — usually on products that are approaching their "best by" date. The label may vary slightly among the Kroger affiliate stores, but Demer says you can usually find these items at the end of aisles or near the stockroom.

8. You don't take advantage of fuel discounts