Use a commercial soap that is specifically designed for washing cars. NEVER use household detergent or dishwashing soaps on cars, as they could potentially damage your car's finish.

Wash your car in the shade whenever possible. This will help the car itself stay cool and will also help to prevent the car from drying quicker than you can wash it, since this will leave spots.

Be sure to mix the soap and water in a bucket, instead of just throwing soap all over the car once it is wet. Make sure you also have a cleaning mitt or sponge handy for the actual washing.

Start by first washing the wheels, one at a time. Use a cleaner specifically designed for wheels, and make sure you hit the tires, rims, and if you have them, whitewalls. Scrub the wheels using a brush. Be sure to thoroughly hose the wheel down before moving to the next one.

Use a spray nozzle on your hose for a nice, even soak of car. Start with the top of the car and work your way down to the bottom. Let the water soak in for a minute or two before beginning the actual washing, as this will help to loosen the dirt.

Start with the roof. Using your sponge or cleaning mitt, try to scrub the roof in straight lines, moving out to the edges of the roof from the innermost part first. Rinse when you are done, and make sure you also rinse your sponge or mitt.

Wash the sides of the car in the same way you washed the hood, using straight strokes while scrubbing the sides from top to bottom. Once again, rinse when you are done, and also rinse your sponge or mitt.

When the sides are washed, move onto the hood and trunk of the car, once again washing and rinsing in the same manner.

After you have washed and rinsed the sides of the car, spray the undercarriage of your car thoroughly, to help remove buildups of mud and dirt.

Once your car is rinsed thoroughly, dry the car using a clean, soft cloth. Have plenty available, as you may need more than one, depending on the size of your car. Do not try to rub out every single drop of water from the surface of the car, but run the cloth over the car lightly to smooth out the water droplets.

CAUTION: On some cars, the charcoal canister filter that helps absorb gasoline vapors from the fuel tank and keeps them from escaping into the atmosphere has ventilation slots in a rear wheel well (for example, most Hyundai Sonatas from 1999 to 2005). Spraying a high-pressure water stream into a rear wheel well can saturate that filter and cause the "CHECK ENGINE" light to go on. In some cases, the filter will dry out and the light turn off after a few days, but in severe cases, you could damage the filter and have an expensive replacement bill on your hands. If you aren't sure where the filter is, check with your mechanic or dealer.