Two buckets, wet the car with first with a bucket of clean water to remove dust then use a bucket of warm water with car shampoo of your choice, rinse off with another bucket of clean water then towel off to dry the car to avoid water spots forming. Once dry you can apply polish or wax of your choice. I have been using car shampoo with built in wax and get good results, rain beads and runs off ok using these types of shampoo. If you want to go the whole hog with polishing and waxing I have used Mer polish for years, large bottle of this lasts years. At work we use Porboys Black Hole on the Hearse and Limos, its very good at filling scratches and produces a high shine when buffed off by hand.