If you have an air fryer, you’re probably making mistakes when it comes to operating and maintaining it. Arguably the biggest mistake you can make with an air fryer is not buying one. Air fryers reduce the cooking time and oil needed, meaning bacon, whole chickens, burgers, and fries are all done in a flash.

Operating an air fryer is easy, but there are a few firm rules to follow to ensure even cooking and maximum deliciousness from your next air fryer creation.

For help, we consulted Empowered Cook’s “Air Fryer Queen” Kathy Yoder to learn about the most common mistakes you may be making with your air fryer.

1. Underestimating your air fryer

The air fryer’s undeniable superpower is its ability to make frozen fried food taste delicious and feel as if it’s actually been deep-fried. However, getting stuck in an air fryer rut is the biggest mistake when it comes to using an air fryer.

“People tend to focus on two things, like chicken nuggets and French fries,” says Yoder. “Aside from frying, if you can grill it or bake it, in most cases you can use your air fryer for that.”

2. Wasting time preheating

This is a hot take, because many air fryer recipes require preheating. That could mean running it empty for a few minutes to warm up its nonstick surface, or some models even have a preheat setting that can take up to five minutes.

Yoder tested several recipes using the same air fryer, both preheated and unpreheated, and found that preheating didn’t make much of a difference.

“It probably makes a difference of two minutes,” she says. “I only preheat too much when something takes very little time to cook.”

Since the purpose of air frying is to save time, minutes matter. Many air fryers with a preheat setting usually don’t have a built-in temperature monitor, so if you accidentally open the basket during the preheat cycle, it will start over, which is a real waste of time. (I’ve experienced this firsthand. It’s really annoying.) Plus, opening the basket after preheating lets all the hot air out anyway.

3. Using nonstick cooking spray

The purpose of an air fryer is to reduce the need for oil, resulting in healthier dishes, but the temptation to use some nonstick cooking spray — even though most air fryers have a nonstick coating on the inside — is real. But it’s a bad idea: “It is said that some of the propellants in cooking spray can damage the coating in the air fryer,” says Yoder. And more: “Look at the ingredients in there. You don’t want to swallow them.”

For foods like raw vegetables that might need a little help from the oil, Yoder recommends simply buying a spray pump and filling it yourself, over a highly convenient option like cooking spray.

4. Using too much oil

Some vegetables that don’t have any fat to begin with might need a little help moving around in the air fryer, but “in most cases, it’s not needed,” Yoder says. Most meats release enough fat on their own during the cooking process: Chicken skin crisps up in the air fryer with just the fat from the meat. Oil can be used in some preparations, but it should be used sparingly.