Here is what I would do (but you'll get other responses):
1. Wash car and dry.
2. Use a clay bar and some quick detail to lubricate. Soap and water is an okay lubricant, but any quick detail is great. Any clay bar will do. Do a section and wipe off with a clean dry microfibre towel.
3. Use Klasse All-In-One (AIO). The directions are easy, and can be applied by hand.
4. Apply a synthetic sealant. I like Meguiars NXT Tech Wax, since it is easy to apply, easy to remove, and cheap (about $0.50-$1/vehicle). I've not tried Poorboy's World EX or EX-P, but I have some and will try it soon. It is not a paste, but a liquid. Klasse also has a sealant that is supposed to be pretty good.
5. A sealant will give up to 6 months of protection. You can feel free to add any Carnauba wax on every month for extra shine and protection. For dark cars, Pinnacle Souveran is good, but don't waste the money on damaged or light cars. Poorboy's Natty Paste Wax (Blue for dark and regular for light cars) is quite good. The Treatment is very easy to use, and comes in a pre-softened paste tube with a great applicator.
6. Wash with a soft cloth or mitt, not a brush. And don't go to brush car washes. Use a non abrasive slick soap and do it often--weekly and after every snow (well, after the next day when the salt is a the peak). If you can't wash yourself, it is worth $10-$15 for a detailer to do it, IMO.