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

More than 310 million people shop on Amazon, and they drop a chunk of change — anywhere from $625 to $1500, on average, each year — snapping up everything from books to beauty products to bananas on the site. In the U.S., an estimated more than 60 million people are Prime members — paying up to $99 per year to get free two-day shipping on thousands of products, as well as other perks.

But many Amazon shoppers are spending more than the should. Here are the Amazon mistakes every deal-conscious shopper should avoid.

Mistake #1: You buy the wrong things on Amazon
Sure, Amazon has some great deals — but not on everything. Cost-conscious shoppers should, in general, avoid buying tires, home goods, cleaning products and clothing and shoes on the site, says Kendal Perez, a savings expert at CouponSherpa.com. Perez notes that household items are often cheaper at places like TJMaxx and Home Goods; cleaning products at Walmart; and clothing at department stores, which have a lot of coupons, and clothing stores. For tires, try warehouse clubs like Costco.

Krista Fabregas, an ecommerce analyst and writer at FitSmallBusiness.com, adds that a bulky paper products like toilet paper, paper towels and printer paper are also typically a no go, as are power tools. For paper products try the dollar store and Target and Walmart; for power tools Lowe’s and Home Depot.

Mistake #2: 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 #3: 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 #4: 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.”

Also see: Amazon just released some of its deals on Prime Day on July 11th