Alexa, how are you going to take my money today?

Amazon announced this week that, come Monday, it would be lowering prices on a lot of popular food items at Whole Foods, including bananas, kale, chicken and more. What’s more, it promised that Amazon Prime members — who pay $99 per year to get two-day-free shipping and other perks on thousands of products — will get additional benefits in the future, including a special customer rewards program, and that Whole Foods private label items like its 365 brand will be sold on Amazon.com.

Amazon likely hopes that the more than 310 million people who shop on Amazon will drop even more money on the site now; already they spend anywhere from $625 to $1500, on average, each year — snapping up everything from books to beauty products to bananas on the site. And it may be hoping that this move can help drive more Prime memberships: In the U.S., an estimated more than 60 million people are already Prime members.

But whether you’re a Whole Foods shopper or not, you may be spending more than the should on Amazon. Here are the Amazon mistakes every deal-conscious shopper should avoid.

 

Mistake #1: You always opt for the “free” two-day shipping
Sometimes you need whatever it is you ordered in two days — but often you don’t. If you don’t, opt for the no-rush shipping. The reason: Amazon often will give you an order discount immediately or a promotional reward towards a future purchase when you do this (you can see the offer at checkout). The downside, your order may take six business days to get to you.

Also see: This new Amazon Prime feature is going to change your life

Mistake #2: You don’t time your purchase right
Amazon’s prices fluctuate often — an analysis by Profitero found that a product’s price changes an average of nearly five times per month, and sometimes more — so if you buy on a whim you might be missing out on the best price. That’s why it’s always worth looking at a price-checking site like CamelCamelCamel.com, which will show you when prices for items tend to be lower and higher, says Courtney Jespersen, a shopping expert at NerdWallet.com — so you can time your purchase accordingly. On the site, you can look at “Top Price Drops,” and find what’s seen a big dip in price; electronics often appear on this page, some of which have price drops of 30% or more.

Don’t “need” the item you’re eyeing? Wait for the deal to come to you, by signing up for Amazon’s “Watch a Deal” service, where you can get notified of its deals and other promotions, says shopping expert Trae Bodge.

Mistake #3: You’ve gotten seduced by Prime
Amazon Prime members — who, for $99 per year, get free two-day shipping on thousands of products, as well as other perks — spend more than double ($1500 vs. $625) what other Amazon customers spend, according to data from Consumer Intelligence Research Partners. The reason: Once you’ve paid that membership fee, you’re committed to them and go there first — often without looking elsewhere: “There’s good reason to believe that people who aren’t Prime members are more likely to shop around and make purchases at Amazon only when it’s clearly the most convenient or cheapest option,” an analysis by Time shows. “They don’t automatically defer to making purchases at Amazon, like Prime members appear to do.”

Mistake #4: You don’t comparison shop
Sure, Amazon has tons of great deals — but not on everything. A 2014 study from Savings.com found that about half the time competitors had lower prices. And that’s why experts say its important to comparison shop on everything from home goods and cleaning products to clothing and paper towels. To make it easy, you can use a simple browser plugin like PriceBlink, which will show you if the item is priced differently at another retailer, and you can look at the items price history on CamelCamelCamel.com.

This story was originally published in July and has been updated.