While many people are concerned with the swirls and scratches in their vehicle, little thought is put toward how they got there. The majority of swirls are considered wash-induced, that is, the act of keeping your car looking good is actually causing damage. This damage is a result of poor wash techniques, of which the following are most common:

Using dirty water
Using dirty wash media
Lack of adequate lubrication on the paint
Poor quality wash media or drying media
Washing panels in the wrong order

Nobody is a perfect car washer and even if you were, by the time you got done washing, a speck of something has landed on the part of the car where you started and you are going to pick it up with your drying media. For this reason, using forced air, blotting or a drying aid are strongly recommended.

Employing best practices for washing your vehicle will reduce the potential for wash-induced defects. The suggestions below are a great start to minimizing defects in your paint.

Use multiple buckets and wash media
Segregate the dirtiest portions of the car to separate wash media and bucket (wheels and lower panels)
If you drop it, down-grade it or throw it away
Wash top-down, from cleanest to dirtiest panels
Frequently rinse your wash media to remove soiling that's been picked up