The first thing you can do is place entry mats in your home. Place them anywhere that you enter your home. This means that you should have one at the front door, at the side door, at the back door and at the garage door. The more the better because it gives people a place to track off dirt before it gets transferred to your carpeting.
Another great thing you can do is to be prepared. Be ready for the occasional spill or mess by having a bucket ready with cleaning supplies. Have in it plenty of spotting towels and a good spot cleaner. You will be more likely to take care of spots as they occur if you have the materials handy. Cleaning spots up as they happen will keep them from overwhelming you.
My third suggestion is for you to rearrange your furniture often. If you leave your furniture in the same place for the entire life of the carpet, the same areas will continue to wear out. If, however, you move your furniture around every six months, you will change the way people walk in your home. This will spread the wear out to different sections of the carpet and will thus increase the life of the carpet.
The last thing you can do to take care of your carpet is to vacuum regularly. At least once a week but more often if your home receives heavy traffic such as houses with kids or with pets. Keep your vacuum well maintained and vacuum slowly and deliberately. You want to go slow to give it a chance to really pull up the dirt from your rug. Be sure to change your vacuum bag when it gets more than half full as well because it begins to lose suction past this point.
That's it. These are three of the best things you can do to maintain your carpeting. If you just do these three simple things you will greatly extend the life of your homes carpet.