A first step in buying carpet is to think through questions such as how much carpeting you need, where it will go, how it will be used, and what will look good with your furnishings. A good carpet store can be a helpful source of advice.

In our ratings of carpet stores and installers, we found that some stores were rated “superior” for the advice they provide by more than 80 percent of the customers we surveyed. But some stores are of little or no help, as indicated by their failure to get “superior” ratings from even half of their surveyed customers.

You not only have to choose the best carpet for your home but also be confident that the carpet will be properly installed. We hear again and again of delivery delays and sloppy installations. Some outlets receive very low scores for installation work from their surveyed customers.

How much you pay—even for the exact same carpet—depends on how and where you shop. Our undercover shoppers found large store-to-store price differences when they asked for price quotes for the same carpet, padding, and installation work. Unfortunately, carpet stores make it extremely difficult to compare prices.

Make sure stores don’t sell you more carpet than you need. And before you close the deal, get a written sales contract. Make all payments by credit card to preserve your rights to get a refund if you're dissatisfied.