(MONEY Magazine) – These days, you can pretty much throw a rock in any direction and hit a forecaster predicting that this year's online holiday shopping season will be the biggest one yet. Sure, the numbers are impressive: $4 billion in online sales, compared with last year's $1.5 billion, according to Forrester Research. But what you really want to know is where can I get a good deal? Is my credit-card number safe? And what else do I need to watch out for? Having written about online shopping for the last year and a half, I've compiled eight of MONEY's favorite tips--and warnings--to help make your holiday shopping a little cheaper, safer and faster.

1. Compare prices the easy way

By far, our favorite way to find a good deal on the Net is through price comparison websites called shopping bots. These services quickly search dozens of retail sites for the lowest price on the product you want, rank the sites by price and link you to them. The best bots also display shipping charges, taxes, availability (which is especially good to know at this time of year) and contact information so that you don't have to surf dozens of slow-loading sites. There are many bots out there, but we'd head to www.dealpilot.com for book, CD and video price comparisons, www.shopper.com for computers and electronics and www.mysimon.com for a wide variety of stuff, including sports equipment, tools and toys.

2. Shipping charges matter

One of the reasons shopping bots are great is that they often disclose the shipping costs. In contrast, some retail sites force you to fill out lengthy forms with your address, phone number and e-mail before they'll factor shipping costs into the price (PC Zone and eToys are two annoying examples). How much of a price difference does shipping make? It varies. On a recent search for a new iMac DV, I found that Outpost.com and MacWarehouse were charging virtually the same price ($1,294 vs. $1,299). Yet MacWarehouse was adding $88.70 for shipping; Outpost.com has free shipping. A warning: Some sites with free shipping (eCost, for example) charge a "handling fee" that can wipe out any savings.

3. Don't expect immediate gratification

When you absolutely, positively need it overnight...the Web may not deliver. Say you want a book from Amazon.com. You can select overnight shipping, but Amazon, like many other retailers, promises to deliver an order overnight from the time the item is shipped. Because many Net retailers don't have all their items in stock (Amazon typically hedges with disclaimers like "Usually ships within 24 hours"), you may pay more for overnight delivery and still not get your item for nearly a week. When this happened to me at Amazon, I called them on it. They directed me to the small print stating their policy but still reimbursed me for the difference between standard and overnight shipping. If you really need a last-minute present, try a gift certificate via e-mail. The $25 one I ordered from CDNow arrived within a few hours.

4. Be prepared for tricky return policies

Buying online is convenient. Returning items often isn't. Some Web stores let you return merchandise to their physical-world counterparts (Gap, Tower Records, Toys R Us), but many won't (Barnes & Noble, Victoria's Secret, CompUSA). And, of course, many online retailers don't even have brick-and-mortar stores. That means if you don't like what you ordered, you'll probably have to pay for return shipping. If you need to return something that was sent to you erroneously, however, don't pay for postage. When I called one retailer about a book I hadn't ordered, they quickly sent a prepaid package to return it in. Also, before you buy, find out how much time you have to return an item; return windows, especially for big-ticket items like computers, have been shrinking.

5. Watch for sales taxes--sometimes

Charging sales tax on Internet purchases is a hot topic these days. Some retailers do, some don't, and legislators around the country are wrestling with setting a national standard. For now, says Seema Williams, an analyst with Forrester Research, a rule of thumb is that retailers who don't charge sales tax usually won't let you return the product to their real-world stores. Many retailers will charge sales tax only if you're ordering from the company's home state. And some bots, including DealPilot.com, display the tax, if there is any, and factor it into the price.

6. Look for watchdog approval

I've found that some online businesses, like regular ones, aren't great when it comes to customer service and ease of use. That's why it's helpful to look for logos of watchdog groups, which indicate that a third party, or even customers themselves, have evaluated the site. If you see a BBBOnLine seal, it means the retailer is a member of the Better Business Bureau, has been in business for at least a year and responds promptly to consumer complaints. If you want to know what other buyers think, go to www.bizrate.com, where consumers rate retailers based on, among other things, service and delivery time.

7. Warranties aren't always a given

Another thing to watch out for is "gray market" merchandise--goods, often electronics or other big-ticket items, that don't come directly from the manufacturer or one of its authorized retailers and therefore don't have manufacturer warranties. As a result, they're often heavily discounted. When in doubt, e-mail the retailer before buying to see if the original warranty still applies or, if not, whether the retailer offers one. For example, World of Watches, which is not an authorized dealer of the high-end watches it sells online, replaces the manufacturer's warranty with one of its own.

8. A credit card is your ally

"Is it safe?" is one of the biggest questions consumers ask and also one of the easiest questions to answer: Yes, assuming you buy from a reputable retailer and use a browser with encryption technology (which is built into newer versions of Netscape Navigator and Microsoft Explorer). Also, don't forget that with a credit card your maximum liability for any kind of theft, online or elsewhere, is $50. And if you report any fraud within 24 hours of discovering it, many issuers won't hold you liable for a single penny.

--ROB TURNER

E-mail your online shopping questions to online_shopping@moneymail.com.