If you accept the car before getting ppf, do NOT use circular motions for its first wash. Get a clay bar, wet the car, and use long straight strokes with the clay in one direction. For example if it's the hood, start at the top at the base of the windshield, then lightly drag the clay bar in a straight line down towards the front. You don't need to use much pressure. You'll feel a slight amount of resistance as it pulls off any surface dust, or irregularities. Keep the surfaces wet; don't do this on a dry surface. After the first pass, do it again until there's no resistance. Move to the next area and continue. On a brand new car, one clay bar should be enough to do the whole car.
DO NOT DROP THE CLAY BAR ON THE GROUND! If you accidentally do, throw it away and get another one. They're not that expensive. The clay will pick up any tiny grains of sand or grit, and then using it on your car is like using sandpaper.
After you clay bar the car, rinse and dry with a microfiber cloth. Once it's thoroughly dry, put a good wax or surface treatment of some kind on it. That will keep it from having swirl marks in it. This is especially important on a car with dark color paint.
If your car goes directly to a place for ppf, they'll do the paint correction and surface prep, which is part of the cost of getting the ppf.