The answer is to avoid touching the paintwork as much as possible. So, very gentle washing with 2-bucket method. Rinsing with resin-filtered water so it doesn't need drying. Avoiding polishing unless absolutely essential (eg polishing out tiny marks, bird poo stains, etc).
PS And never let anyone else touch it. Always specify when taking it for service that you don't want them to wash it.
PPS But, at the end of the day, taking good care of the paintwork won't make it worth any more when you sell or trade it. The only benefit is your own pleasure in having a swirl-free car.