don't bother with a "wax". Get a sealant or a synthetic wax. Some sort of polymer wax. Polymer bonds with the paint, lasts much longer. The key to polymer is to let it sit on the vehicle for a couple hours. Longer you let it sit the better it bonds. I used to wash, clean the paint with a cleaning wax (not really a wax), polish scratches out, polish the paint (to blend and smooth) and then I would apply the sealant and let it sit overnight. Probably overkill but it works.
When waxing use a dishsoap to wash the vehicle. Dish soap does a great job of dissolving the wax. Don't use dish soap after you've waxed for general washing it will wear down the wax sooner.
This is were I buy my products:
http://www.prowax.com/