Last year, Amazon's annual mega sale was pushed from summer to fall due to the pandemic. But Amazon Prime Day is back to its summer roots for 48 hours on June 21-22.

The retailer will be offering more than 2 million deals, making it the largest Prime Day since it began in 2015, according to Amazon.

Data suggests that people are itching to spend, too: In a recent McKinsey survey about consumer sentiment during the pandemic, more than 50% of U.S. consumers said they planned to spend extra cash by splurging or treating themselves post-Covid, especially higher-income millennials (82%).

There's a "pent-up demand" to spend money now that people's daily lives are approaching normal, says Anthony Dukes, professor of marketing at the Marshall School of Business at the University of Southern California.

Navigating Prime Day requires strategy regardless of the year. Here are four common shopping mistakes to avoid making this Amazon Prime Day:

Don't give into the pressure to act fast

Amazon, like many online retailers, uses a few savvy marketing tactics that "activate shoppers" and make products seem more enticing, Dukes says. For starters, Prime Day "feels like something you should be a part of simply because it's an event," he says. (This is also true of Black Friday, for example.)

There's a "perishable quality" to Prime Day because it only lasts 48 hours, Dukes says. The time restriction increases urgency, which makes you feel like you have to act and shop. For example, some of Amazon's "Lightning Deals" display a countdown clock that encourages you to buy something before the minutes run out.

"Scarcity is one of the most persuasive techniques that marketers use," Kelly Haws, consumer psychology expert and Vanderbilt University marketing professor previously told CNBC Make It.

The best way to prevent buyer's remorse is to ask yourself: "Will I use this item in three months?" Think about the potential outcomes and consequences of a purchase, Haws says.

Skip gaming consoles and holiday items

Amazon Prime Day deals are typically "very seasonal because it wants to capitalize on what people are thinking of buying," says Kristin McGrath, editor and shopping expert at BlackFriday.com. Expect to see lots of summer home and clothing items at discounted prices, she adds.

In some cases, it's worth it to wait for other sales to shop, like back-to-school or Black Friday, according to Sarah Skirboll, shopping and trends expert at RetailMeNot.

Skirboll says you should avoid buying video game consoles, toys, Apple products and cameras on Prime Day, because the discounts tend to be more substantial later in the year.

Instead, go for smart home devices, laptops, fashion, beauty, pet products, tools and toys, she suggests. (Also, Amazon-owned items, such as the Amazon Alexa and Amazon Halo fitness tracker, will likely be very discounted, she says.) 

Last year, when Prime Day fell in October, the top-selling items in the U.S. were: the iRobot Roomba Robot Vacuum, MyQ Wireless & WiFi Enabled Smart Garage Door Opener, LifeStraw Personal Water Filter, Goli Apple Cider Vinegar Vitamins and Kids Against Maturity: Card Game for Kids and Families.

On Prime Day in July 2019, the best sellers were the LifeStraw Personal Water Filter, Instant Pot DUO60 and 23andMe Health + Ancestry kits.

Don't fall into the 'discount' trap

There's a phenomenon called "reference price effect," which essentially means that consumers are drawn to a product that's marketed at a discounted price, Dukes says. Even if the discount is infinitesimal, people are more willing to buy a product that they perceive to be on sale, because consumers feel like they're getting an extra value, he says.

"The most important thing for consumers to do is to just make an old-fashioned list before they go in, with things that they have been meaning to buy or stock up on" and stick to it, McGrath says.

Don't forget about other retailers

Not an Amazon Prime member? A handful of large retailers are also offering rival sales events this weekend. Target's Deal Days runs for three days from June 20-22, Best Buy's Bigger Deal Savings Event is happening now until June 22 and Walmart's annual Deals for Days will take place June 20-23.

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