well the most routine thing is to get car washed by normal water 3-4 times a week, wax it once in 2-3 months and during services they do wash and wax, so professionally they would add better finish on your maintained paint, if you are going to park your vehicle for longer duration under the sun, get a car cover and put it on.
Also before waxing/polishing make sure you remove all dirt and there;s no dust particle on the metal before waxing, cause it would rather make it worst if caught along waxing the body, leave a scratch on its body.