~ some personal suggestions...

once washed & out of the sunlight... i would (at minimum) apply a coat of quality carnauba paste wax... a meguiars wax product preferably.

preferred wax/glaze link: http://www.cleanacar.com/meg159.html

a few tips when waxing... apply a thin coat of wax to a moistened foam applicator pad... one panel at a time... remove the wax immediately while the wax is still wet... using a micro fiber towel to remove and polish surface to a luster.

you can also apply the same wax to your rims for added protection. you may want to switch to "rotex gold" dust-free pads for ease of clean & upkeep... a "search" will provide needed info.

if the paint surface feels rough in any way to the touch of your hand after washing... you may want to "clay" your car with a product called: "clay magic" ...
or like product.

as for a schedule... i would wash my car on a weekly basis if driven regularly... i prefer a quality .25 car wash (diy) for the ability to wash/rinse the underside and wheel wells areas.

i would recommend waxing your car quarterly (every 3 months or so) to keep the cars finish protected.

as for paint/surface touch-ups... i would use a "quick detailer" spray with a micro fiber towel.

hope this helps!

andrew