The single most important thing you can do to make your carpeting last is vacuum it on a regular basis. This is also probably the most neglected step in carpet care. By vacuuming your carpet, you will be removing dangerous soil from your rugs. Soil that would otherwise wear and abrade the carpet fibers every time you step on it. If you do nothing else to increase your carpet life, vacuum.
Another great way to protect your carpeting is to place entry rugs wherever your carpet meets hard surface. This will give your family and friends a place to transfer soil to before they walk on your rugs. Place the rugs on the hard surface and not the carpet. if you place it on the carpeting, you might get a soil line around it.
A third method of protecting your carpet is to rearrange the furniture often. it is not as easy as the other methods but it pays big dividends. By moving furniture around you change the way traffic flows through the room. This keeps you and your family from wearing out the same exact area of carpet. You instead spread the wear around.
Lastly, have your carpet cleaned often. Do not wait until it is too dirty to look at any more. Set yourself up on a cleaning schedule where you clean it at regular intervals. If you wait too long, stains will set in and your carpet will become irreversibly worn.
These may seem like small things for you to do but they can greatly improve the lifespan of your carpet. So take the time to take care of your carpet and you will get years of enjoyment out of it.