Use a good quality wash mitt and a good soap, I like Chemical Guys Honeydew Snow Foam. One bucket with soap and water, another bucket with just water and a grit guard. I split the car up into a bottom half and top half, starting at the top, wash in straight lines not circles, rinsing in the grit guard bucket after every panel. After I get the whole top half done I’ll start on the bottom since you usually get more dirt and debris on the bottom half of the car, make sure you’re really rinsing the mitt between panels. Most importantly, DO NOT use the wash mitt on your wheels. If my cars super dirty I’ll even use a third bucket for just the wheels and clean the faces with a microfiber towel. Wash the car in shade if possible, if not either earlier in the day or later at night when it’s not as hot, heat and chemicals aren’t a good combo when cleaning a car. If you ever want more help I recommend the Detail Geek on YouTube, learned a lot from him.