A Costco membership opens doors, quite literally, to a vast selection of bulk-size groceries and household goods selling at discounted prices. But buying potato chips and toilet paper by the case is just the start. The warehouse club also stocks everything from tires and furniture to electronics and jewelry. With so many items to choose from, Trae Bodge, a consumer expert who specializes in smart shopping strategies, says it's critical to shop Costco with a list to avoid overspending.

List or no list, shoppers seem to like the savings and selection. Costco has 50 million paid members around the world, with an 87% renewal rate worldwide (90% in the U.S. and Canada). The chain ranks first in customer satisfaction among department and discount stores, according to the American Customer Satisfaction Index, edging out rivals Sam's Club and BJ's Wholesale.

Thinking of taking the Costco plunge? Here's what you should know before investing $60 in an annual membership.

You Don't Actually Need to Be a Member to Shop

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If you're not ready to commit to a year-long membership, there are still ways to shop at Costco. Members are allowed to bring up to two guests. So if you want to check out the warehouse club to see the selection and compare prices, ask a friend or family member with a membership if you can tag along. Want to buy something? The Costco member will need to make the purchase for you -- cashiers check membership cards at checkout -- but afterward you can simply pay the person back.

If you want to shop on your own without a membership, give that same friend or family member the money to purchase a Costco Cash Card