2-Bucket Car Washing Technique
This method helps to prevent swirl marks caused by poor washing technique.

Park vehicle under shade and let paint surface cool to the touch, prepare 2 buckets of clean water and washing spone/mitt.

Thoroughly rinse the entire vehicle before washing begins. Add car shampoo to bucket #1 and lather to foam. Start washing the car, remember, starting at the roof top area, then trunk, then hood, then sides.

Each time you're ready to reload your sponge/mitt with soapy water, dunk it vigorously in the clean water first (bucket #2), to rinse out the grit and contamination you've just removed from your vehicle from possibly further scratching the surface. Then dip it in the soapy water (bucket #1) to reload and continue washing. Rinse and reload your Sponge as often as you can to prevent cross-contamination.

If possible, use a separate sponge/mitt to wash the sides, especially the lower or rocker panels.

Rinse and dry vehicle. Job done!