As others have stated if you allow water to dry on the car, you get water spots. I use compressed air to blow the water out of the nooks that it likes to drip out of after you wash - emblems, mirrors, rear valance, stop lights, etc.
Autogeek.net has lots of things to spend your money on as MB suggested. And true true true you get what you pay for. In addition to Val's routine I use a paint sealant twice a year.