If you're shopping the Internet for home products like flooring, furniture, carpet, fireplaces, grills or even power tools: Look, but don't buy.

Buying any of these online could invalidate or limit the warranty that the manufacturer usually offers with the product.

My advice: Browse the Internet all you want to get an idea of different styles and colors. But when you're ready to buy a major home-improvement item, visit a local dealer who is authorized by the manufacturer to sell the product. Discuss your choices with the expert, take a look at the product up close and touch it. Then place your order--with the brick-and-mortar store you know will deliver it safely and stand behind the quality of the product and its installation.

More and more manufacturers are refusing to honor warranties on products that consumers buy online and install themselves. It's too hard to police the quality of shipping and installation--and to even know if the product you're getting was really made by the company whose name is on the box.

Still, if you're determined to shop for home-improvement products online, keep yourself out of trouble by following a few guidelines:

• Know that manufacturers charge online dealers the same amount for a product as physical store owners pay for it. So if the online shop is charging way less, something's wrong. It's possible that the product you're getting is not the genuine article.
• Do not accept merchandise without its original box. In order to qualify for rebates and get the information you need for your warranty, you need the codes that are printed on the outside of the box. Plus, if you try to return an item without its box, you might have to pay a hefty restocking fee.
• Forget buying anything oversized or heavy online unless the seller agrees to pay for shipping. Otherwise, you could wind up paying nearly as much for shipping as you do for the product. And if you need to return or exchange it, you could get stuck with that shipping charge twice.
• If your heart is set on a specific color or pattern, find a physical store that has the product so you can see it in "person" before you buy it from an online seller. Colors do not appear realistically on a computer screen.
• Pay for your purchase with a charge card that will insure you and the product or at least investigate a rip-off or a complaint that you can't resolve with the seller.
• Avoid buying from online sellers you've never heard of. Your best bet: Shop the Web sites of name-brand stores.
• Look on the manufacturer's Web site for an Internet Sales Policy. This will tell you if the product maker will honor the warranty of an item that you buy online.