I’ve been a proud Costco warehouse member for more than a decade, and it’s my favorite place to stock up on household items at a fraction of the cost, especially when it comes to essentials like toilet paper, olive oil, and meat.

For me, shopping at Costco requires a plan of action before entering the warehouse, because it’s easy to overspend when you’re walking around looking at all the items that are unique to their warehouses. I’m looking at you, in-house bakery section.

That said, in talking with friends and family, I’ve noticed plenty of membership mistakes people are making—namely, not taking full advantage of the perks you’re afforded by joining. 

13 Costco Mistakes To Avoid During Your Next Trip

If you’re planning to take full advantage of Costco this year, don’t make these top mistakes.

1. Not upgrading your membership.

If you are a frequent Costco shopper, it might be smart to consider upgrading your membership from Gold Star to Executive. The most affordable membership (Gold Star) offers warehouse access for just $65, but if you’re making multiple trips to Costco per month, the 2% cash back incentive offered with the Executive membership tier ($130) is worthwhile. This incentive means Executive-level Costco shoppers can earn up to $1,250 each year.

2. Forgetting to fill up your tank.

After you’ve filled your cart, be sure to fill your tank. Most Costco locations have gas pumps and offer very competitive pricing with some reports stating up to 20 cents cheaper per gallon. Use the Costco app to find warehouse locations near you that offer it, what the gas prices are, and hours of operation.

3. Overlooking Kirkland brand products.

Costco has its own in-house brand (Kirkland Signature) that offers quality products at a fraction of name-brand items. For example, Kirkland’s Extra Virgin Olive Oil is consistently rated a best seller and a favorite among shoppers for both quality and price. A 2-liter bottle runs about .47/ounce comparative to premium olive oils that can get up to $2/ounce.

4. Not shopping online.

All Costco membership tiers—Executive, Business, and Gold Star—offer access to Costco.com, which is a gold mine of great deals, some of which are exclusive to the website. 

5. Looking for the coupons.

Coupons? On top of already reduced bulk pricing? You bet. Each month, Costco releases “Members Only Savings” booklets that feature all the sales and promotions occurring in the warehouse. It’s a great time to stock up on items you know you’ll always need, such as laundry detergent or soap.

6. Paying attention to the price tag.

When shopping in the warehouse, Costco price tags are often indicators of much more than the price. Standard pricing ends in nine (think $19.99), but sale items end in zero or seven (think $19.00 or $19.97). When a price tag features an asterisk, stock up; it means that product is leaving the warehouse soon.

7. Not utilizing Costco’s return policy.

Costco offers members a generous return policy, 100% customer satisfaction, which means that if you don’t love something you’ve purchased, you can take it back to the warehouse. Worth noting, it’s important not to abuse this policy as frequent returning of items can get your account flagged.

8. Buying more than you can use.

While Costco offers tremendous deals, they’re only good if you’ll actually use the products. For example, buying meat in bulk may seem like a good price for your household, but if you don’t use it or freeze it and half the pack spoils, you’ve wasted your money. The same goes for produce and bakery items like bagels and muffins. Make smart choices about what you’ll actually use or if you have room to freeze it.

9. Not taking advantage of gift cards.

Costco offers gift cards to many popular restaurants, stores, and even some travel brands, so if there is a place you frequent—or you’re looking to stock up for gifting—it’s smart to invest in buying gift cards at discounted prices.

10. Forgetting about price matching.

That’s right—in addition to low prices, Costco will price match within 30 days. So if something you purchased gets steeply discounted a few weeks later, you can return to any warehouse with proof of purchase to be refunded.

11. Not checking your local grocer’s prices first.

It’s true that Costco offers great deals on everyday items, but it’s not always the cheapest option. Buy-one-get-one deals at local grocers can often be a better deal than Costco and lead to overspending when you’re trying to save.

12. Overlooking the clothing section.

Costco warehouses may be best known for bulk products at cheap prices, but at the center of the store lies an often missed opportunity for great deals: the clothing section. From basics like t-shirts and leggings to coats and swimwear, Costco carries recognizable brands like Patagonia, Banana Republic, and 32 Degrees. It will have you saying, “Thanks, I got it at Costco!” 

13. Forgetting about the pharmacy.

Not only do Costco pharmacies offer hundreds of generic drug brands priced at $10 or less, they also offer immunization services and a full Hearing Aid Center. Not a Costco member yet? You do not need a membership to use Costco Pharmacy.