Scrub your car from the top down. Don't press too hard on the mitt -- you want to avoid grinding in dirt that could scratch the paint. As you wash, it's important to keep the car wet, especially when you get to difficult patches such as bird droppings and sap. Use your hose to mist the car as needed. Sap can be removed with gentle thumb-nail pressure, but be careful not to get over-zealous and scratch the car.
Don't ignore small cracks and crevices, as these are places where dirt loves to collect. The wash mitt allows you to apply finger-tip pressure to many of these spots, but some areas may require a detail brush or a bit of improvisation. Be gentle when using a detail brush -- you don't want to scratch the paint or damage old, brittle seals.
Products used:
Sheepskin wash mitt (compare prices)
Microfiber wash mitt (compare prices)
