once a week
use good microfibers
quality waxes like meguiars, 3M, collinite
and use washing liquid, meguiars, chemical guys etc
ánd yes, prefer 100-105 bar pressure washer (pioneer, Karcher K2, black n decker or any other )
degreaser underhood wil work fine
protect parts from rust etc\
and within a month, get underbody washed once