^^^What they said
but really its all proper wash and drying technique after that...typically where most swirls and light scratches are introduced into the paint unfortunately.
Find a quality car wash/soap. Rinse vehicle thoroughly. Use a 2BM (two bucket method). Panel at a time. Rinse mitt/wash media well every time. rinse well. Use a quality waffle weave microfiber to dry or to dry in a touchless manner then use the Metro Blaster Sidekick.
Other may have other recommendations. I personally rinse, foam cannon the car, rinse, foam again and use 2BM and use two different mitts. One for lower panels of car and another for rest. Is it overkill? probably...but I do this for fun and as a hobby...I'm no pro..so time is on my side, most of the time