i) Give the car a really good wash and wax and then,
ii) Give the car a quick wipe over with a California Car Duster every evening (takes literally 30 seconds).
iii) Wipe off any marks etc with quick detailer spray and a microfibre cloth.
If the weather stays dry and there is no mud on the car I can keep the car clean for several weeks this way without a full wash. I do tend to give the wheels a wash more often though to get rid of the dreaded black dust.