Frequent shoppers know best.

Once upon a time, in a Land Before Costco, our office and school supply closet wasn't also storage for extra toilet paper and our basement wasn't a display case for all the Kirkland Signature items that couldn't fit in the pantry.

These days, Costco is our go-to for shopping of all kinds — from alcohol and furniture to beauty products and frozen food — but hitting the big box store can still feel overwhelming. Where to start? Should we pick up holiday decorations this early? Boy, does that sample station look good! Where can I find the...?

While Costco employees certainly know their fair share of secrets, there's another source of Costco intel: Frequent shoppers. Reader's Digest recently rounded up 13 Costco tips frequent shoppers keep to themselves and we were surprised and delighted by some of the advice. Here are our three favorite tips:

1. You can score a Costco membership deal on Groupon.

"If you're not sure you're ready to commit to a full-priced Costco membership, wait for one to go on sale. The warehouse partners with Groupon about once a year to provide discounted Gold Star memberships. This year's deal included $20 in Costco Cash and $65 in coupons," writes Juliana LaBianca. To make sure you don't miss out on the sale, set up a Google alert for "Costco" and "Groupon."

2. Shop at a Costco Business Center.

Yes, it's a thing, and a wonderful thing at that. "Wish you could do your shopping before work? You're probably out of luck with most Costco Wholesale stores, which tend to open at 10 a.m. But if you live near a Costco Business Center you might have an easier time," explains LaBianca. "These stores cater to business owners (although they're open to everyone!) and open earlier, around 7 a.m. They're also organized more straightforwardly, to cater to buyers who need to get in and out as fast as possible."

3. To save time, ask an employee for directions.

Time is money, and spending extra time wandering aisles aimlessly searching for the peanut butter can lead to impulse purchases you wouldn't have otherwise considered. "One way Costco gets you to spend more is by consistently moving things around the store," LaBianca comments. "Things that don't require refrigeration tend to get moved a ton," shared a Reddit user. "So I would always ask before giving up or spending 45 minutes wandering around."

Be right back, time to make our shopping list.