Here's a step-by-step guide on how to wash a car properly:

1 Fill a bucket with soapy water. You can use a specialized car wash soap or a mixture of dish soap and water. 

2 Rinse the car thoroughly with a hose to remove loose dirt and debris. 

3 Dip a soft mitt or sponge into the soapy water and wash one section of the car at a time, starting from the top and working your way down. Avoid using a rough cloth that could scratch the paint. 

4 Rinse the soap off with a hose or bucket of clean water before it dries on the car's surface. 

5 Repeat the process for the rest of the car, rinsing the cloth or sponge frequently to avoid scratching the paint with dirt. 

6 Use a different cloth or a designated rag to wash the wheels and tires, as these areas are often the dirtiest and may contain brake dust that can damage the paint. 

7 Rinse the car one last time with clean water, making sure to remove all soap suds. 

8 Use a chamois or microfiber towel to dry the car, starting from the top and working your way down to avoid water spots. 

Note: It's best to wash your car in the shade to avoid soap drying on the surface in the sun and creating water spots.