Vacuum:

Vacuum frequently. By vacuuming carpet you remove damaging grit that wears down carpet it also removes soils before they build up. I still prefer a bag based vacuum over a bag less and a well made lighter unit. My personal choices are a Sanitaire for work and a Riccar for home. But really most issues are from having an older broken unit and even a new 60.00 vacuum will beat an older poorly maintained unit.

Carpet Cleaning

Truck mounted steam or hot water extraction (same thing) is recommended once per year. Hot water extraction is the proper name for steam cleaning and the industry has been trying to change it for years but it is the same thing. Its actually hot water that hits the carpet not steam and its extracted through a strong truck mounted vacuum not left on the carpet. So the name makes sense its just not in full use yet. And truck mounted hot water extraction is a pretty big mouthful.

So what is the recommended carpet cleaning process? The cleaning industry allows numerous cleaning methods so does not discriminate. To get a quantitative answer we must go to the carpet manufactures websites directly. They have the most to gain as they are protecting their product. While some list processes other then steam they are the smaller carpet manufacturers which generally make specialty rugs and not wall to wall residential carpet. There are 3 carpet manufacturers that are responsible for about 90% of all US carpet, so they are the three to pay attention to.

All three recommend hot water extraction (steam) as their preferred method.   Here are the links to the actual carpet manufacturers to see for yourself. Shaw, Beaulieu and Mohawk (calls it deep cleaning).  The carpet and rug institute (CRI) which was founded by carpet manufactures developed a standard for carpet cleaning and maintenance and can be found here  CRI 205 standards This document only mention HWE as a cleaning method and wants all chemicals to be rinsed/extracted which is my method.