Im looking to buy a body shop so I spend a few days at each one getting to see how things work. the best tip I have seen is they use Tide Laundry detergent ( The LIQUID NOT THE GRAINS!!!!!!!!!!!) in water about 80/20.. You need about 2 cups of detergent to do the entire car. It picks up water spots and gives you a great surface to clay! try it sometime! I'll show some after pictures of a 98 accord that was never waxed once in its life! I thought it needed to be resprayed honestly but it looks amazing now!