5 Mistakes I Used to Make as a Costco Newbie -- and How I Avoid Them Today

One of the first things I did when I moved to the suburbs about 18 years ago was join Costco. At this point in my life, I consider myself somewhat of a Costco maven. But back in those early days, I made my fair share of Costco shopping mistakes. Here are a few I've thankfully learned to avoid -- and perhaps by reading this, you can avoid them to begin with.

1. Sticking with a basic membership

I was a Costco member for years before I did the math on the Executive membership and realized the upgrade totally made sense. To avoid losing out on cash back from Costco, don't be cheap like me and stick to the less expensive membership just because. Instead, actually run the numbers.

These days, an Executive membership costs twice as much as a basic one -- $120 versus $60 per year. But simple math will show you that it takes $3,000 in annual Costco spending, or $250 a month, to break even on the $60 upgrade cost.

So if you're spending even a dollar more than $3,000 per year, the upgraded membership actually makes sense. I still kick myself for failing to do that simple calculation for years -- because I'm sure I missed out on a ton of cash back.

2. Not giving Kirkland products a try

As a Costco newbie, I largely limited my purchase to brands I knew and loved. One day, I tried the Kirkland version of a few things on a whim, and lo and behold -- I was getting the same quality of items at a much lower price.

These days, you can save big on a host of Costco buys by opting for the Kirkland version. So if you're worried about taking a chance on the Kirkland brand, do it for this reason -- Costco will always take your purchase back if you aren't satisfied with it. So there's really no risk involved whatsoever.

If it turns out your $0.32 Kirkland coffee pods really don't taste as good as the Starbucks brand pods you can buy for $0.60 apiece instead, just take back the mostly unused package, and Costco will give you a full refund. But if it turns out you're a fan of Kirkland coffee, guess what? You've just loaded up on a supply of pods for roughly half the price.

These days, I'll buy the Kirkland version of pretty much anything knowing that if it's truly a dud, I'm covered. That said, you don't want to buy Kirkland paper towels if the store has Bounty available. Just trust me on this one.

3. Overbuying non-perishables

When I first joined Costco, I didn't shop there very often. As such, I often erred on the side of buying extra snacks thinking that way, I'd have a supply to last a while.

Here's the problem with buying a massive bag of tortilla chips, though, when you only eat a handful of chips every few days. Even though those chips might last two months in theory, once you open the bag, they can go stale pretty quickly.

These days, I'm more careful with bulk non-perishables. Basically, if I don't think my household can finish the bag within about a week, I pass.

Since I now have three kids under my roof, snacks like tortilla chips tend to get eaten pretty quickly. But if it's just you, or you and a partner, be careful with shelf-stable items. Just because the sell-by date is two months out doesn't mean you won't be risking throwing some of your haul away.

4. Assuming Costco has the best deals available

In my earlier days of shopping at Costco, I fell into the habit of assuming Costco's prices were always the best. I've since learned that certain items can usually be found for less in the supermarket.

Your experience may differ from mine, but most of the time, it makes more sense for me to buy pasta, condiments, and cereal at my local supermarket than at Costco because they tend to go on sale pretty frequently. I learned this by getting into the habit of researching prices and learning when certain items tend to go on sale at my regular supermarket. Before you get into the habit of buying all of your groceries at Costco, do some research like I did to make sure you're not overpaying for the items you buy all the time.

5. Shopping at the worst possible times

When I first joined Costco, my husband and I liked to shop there together. But since he worked in an office five days a week, our sole option was to shop on weekends. And that's pretty much the worst time to go to Costco, since it's when the store is almost guaranteed to be packed.

As someone who's always hated crowds (you can imagine how much I enjoyed the pandemic), I used to rush through my weekend Costco shopping just to get out of there as quickly as possible. And in doing so, I often made mistakes that cost me in one way or another, like not checking expiration dates or buying items on a whim without thinking them through. So now, as a rule, I won't set foot in a Costco on a Saturday or Sunday.

If you have zero flexibility in your schedule, you might have to shop at Costco on weekends. Otherwise, do yourself a huge favor and go during the week, even if it means making an 8 p.m. Costco run. Chances are, you'll be able to tackle your shopping with less stress, which could lead to smarter choices and less wasted money.

I've certainly made my share of mistakes during my Costco shopping, especially in those early days of having a membership. But now that you know what pitfalls to avoid, you may not have to go the same route as I did as a new Costco member.