Here is a good web site "how to" look after a car. They do sell products but I have found the information very helpful. (wrt to clay bars - be very careful).

http://www.carcareonline.com/howto.aspx

http://www.carcareonline.com/viewarticle.aspx?art=5

http://www.carcareonline.com/viewarticle.aspx?art=0