Hand wash or use a brushless car wash.
Do not wash your vehicle in direct sunlight. Water droplets act as a magnifying glass for the harmful UV rays of the sun to fade the finish.
Use a mild car wash detergent.
Remove any stains or bird droppings as soon as possible to prevent any acid etching of the finish.
Avoid exposure to gasoline or antifreeze since long term exposure can damage the paint.
Do not wipe with a dry cloth because together with dirt, dust, and sand, it acts like sandpaper and scratches the finish.
Do not scrape ice or snow from the paint as this can also scratch the finish.
Keep in mind, the average new clear-coat finish on a vehicle is only 4.5 mills thick--that's the same thickness of two sheets of newspaper!
Frequent waxes are necessary to protect the finish. In most cases, a good quality carnauba-based wax (in either paste or liquid form) will provide protection for three or four months. If your vehicle is continually exposed to the elements more frequent waxes may be necessary.
Remember not to wax any area that has been repaired and repainted in the past 90 days per manufacturer recommendations.