The United States has a huge DIY culture. From DIY home improvements, DIY vehicle restorations, and even DIY alternative energy — Americans will do it ourselves if we can. But even if you’re not a die-hard DIYer, chances are you’ve washed and detailed your cars before. Considering it can cost between $50 and $300 for a professional detailing job, learning how to do it yourself would save you a lot of money.

Sure, washing your car isn’t rocket science, but whatever you do, don’t do the following. It’ll ruin your paint job.

1. Never use just any rag or towel when washing your car

According to the auto insurance company Geico, “Don’t use just any old t-shirt, towel, or rag” to wash your car’s exterior. These materials are cheap and easy to come by. But they’re far from being a replacement for professional-grade towels or sponges. Professional detailers typically use a microfiber cloth, which is easier on your car’s paint.

Use a microfiber chenille noodle mitt for a gentle wash, Geico recommends. A chenille mitt is not only much softer than cotton but also more absorbent than sheepskin washing mitts. The added softness allows the chenille to glide frictionlessly over the car’s exterior. It requires fewer wipes, saving you time, energy, and wear on the exterior paint.

“For a fast, streak-free finish, use two waffle-weave towels and wipe off as much glass cleaner as you can with the first towel, then buff away any last drops or streaks with the second,” the author continues.

2. Never use a circular motion

Avoid using circular motions when washing or drying your vehicle. Circular wiping introduces superfine scratches on the paint or clear coat. Over time, these scratches will become more noticeable and harder to smooth out. And it turns out that when it comes to waxing your car, Mr. Miyagi was wrong.

Waxing in circular motions will only result in blemishes messing up your wax job. Rather, it’s better to wash, rinse, and wax in straight lines or Z patterns (if you get bored of moving in straight lines). Reserve circular motions for people who don’t keep their hands to themselves — hands on, hands off.

“An accidental scratch in a straight line will be easier to touch up,” Geico adds.

3. Never let any rags touch the ground

According to car washing guidance from the National Automotive Parts Association (better known as NAPA), don’t let anything you use to wash your car’s exterior touch the ground. It’s a good idea to use the “three-bucket method” so that you don’t spread dirt and contaminants from the grimier surfaces of your car — like from your dirty wheels. Failing to thoroughly wash your mitt, drying cloth, or detailing rag after it makes contact with the ground guarantees scratches and “spiderwebs” in your paint.

We’re not merely suggesting you give it a few dips in the bucket or rinse it under the faucet — to be totally sure, machine-wash it first. But the best thing to do is prevent it from happening by using both hands when washing, drying, and detailing.

4. Never wash your car in direct sunlight

There’s a reason why professional car washes provide shade from direct sunlight. And, no, those awnings aren’t to keep you from sweating. NAPA says that most professional detailers advise “against washing your car on a bright, sunny day.” But because almost everyone prefers to wash their cars on bright, sunny days, be sure to do it under the shade of a tree or carport.

Your vehicle needs to stay as wet as possible during washing. “Keeping the car wet with a light drizzle of water, parking in the shade, or washing in the early evening will prevent spots from forming,” NAPA explains. “It’s also important to rinse with an indirect spray instead of a jet blast of water.”

Additionally, if the soap water dries too fast, you’ll end up with annoying spots covering nearly every inch of your “freshly” washed vehicle.

5. Never wear jewelry or clothing with exposed zippers

The final bit of advice: Wear “car-friendly clothes” when washing the exterior, Geico suggests. Avoid clothing such as zip-up jackets and pants with buttons exposed in the front, as well as accessories such as belt buckles, necklaces, bracelets, and rings.

Geico goes as far as advising you to wear a microfiber apron.

“While it may seem overzealous to put on a car-washing outfit … even buttons can scratch [the] paint.”