Here's here it gets simple. I wash the car, and then carefully dry it.

Washing

I'm using some cheap car wash concentrate that seems to work pretty well.  The best evidence is on the windows, where I use this stuff to clean.  They're perfectly clean with no residue, so I assume the same goes for my paint.

Drying

Drying employes two tools, the water blade and the Aborber:

The water blade is just a wide soft squeegee, and works really well for quickly slicking water off large flat surfaces.  The Absorber then gets all the non-flat areas the water blade couldn't get to.  I've used chamois many times before, and they'll always leave a little bit of water residue on the paint, which will dry and leave mineral deposits.  With one pass, the Absorber soaks up all the water.  It's good product.

It's important to dry the car as well as possible.  Open and shut all the doors, flicking the door handles a few times.  Do the same for the hood and trunk, too.  Water is hiding in every nook and cranny just waiting to come out when you're applying polish.