My approach is one heavy duty step ladders (less inclined to wobble than light weight ones),a bucket of reasonable hot water with a few drips of fairy liquid,just enough to lubricate the water,that way I don't smear the windows with this and the solution is not strong enough to strip off the wax that's been previously applied.
The vehicle is parked up on full lock so I can use the wheels as a platform to reach across the windscreen easily and get a good start on the roof.
With a good quality large cellulose sponge I get to work washing (I avoid using the cheap sponges that after dipping in water wants to roll out all the way down your arm when raised up) using plenty of water and turning the sponge frequently making sure sponge doesn't get gritted.
Wheels left till last for obvious reasons.
If the vehicle is a bit caked up with mud I loosely clean first then change water and start again.
Dry sponge and leather off in sections.....and walla one gleaming Cali
I never use a power wash except for maybe the wheels (call me old fashion ) I just think it forces water into areas that could encourage corrosion
Regards
Alan