Q. What should I know before I bid in an online auction?

A. Despite complaints of fraud, online auctions remain a fun, efficient and relatively safe way to do business — if you act prudently. Here’s how:

Before Bidding
Become familiar with the auction site. Never assume that the rules of one auction site apply to another. If the site offers a step-by-step tutorial on the bidding process, do it. It may save you frustration and disappointment later.

Find out what protections the auction site offers buyers. Some sites provide free insurance or guarantees for items that are undelivered, not authentic or not what the seller claimed.

Know exactly what you’re bidding on. Read the seller’s description of the item or service, and if a photograph is posted, look at it. Read the fine print. Look for words like “refurbished,” “close out,” “discontinued” or “off-brand” — especially when shopping for computer or electronic equipment — to get a better idea of the condition of the item being auctioned.

Try to determine the relative value of an item before you bid. Be skeptical if the price sounds too low to be realistic. “Brick-and-mortar” stores and price comparison sites may be good for reality checks.

Find out all you can about the seller. Avoid doing business with sellers you can’t identify, especially those who try to lure you off the auction site with promises of a better deal. Be aware that some fraudulent sellers may use a forged email header that makes follow-up difficult, if not impossible.

Get the seller’s telephone number so that you have another way to get in touch. Dial the number to confirm that it is correct. Some auction sites post feedback ratings of sellers based on comments by other buyers. Check them out. Although these comments and ratings may give you some idea of how you’ll be treated, know that sometimes, comments may be submitted by the seller or “shills” paid by the seller.

Consider whether the item comes with a warranty and whether follow-up service is available if you need it. Many sellers don’t have the expertise or facilities to provide services for the goods they sell. If this is the case with your seller, be sure you’re willing to forfeit that protection before placing a bid.

Find out who pays for shipping and delivery. Generally, sellers specify the cost of shipping and give buyers the option for express delivery at an additional cost. If you’re uncertain about shipping costs, check with the seller before you bid.

Check on the seller’s return policy. Can you return the item for a full refund if you’re not satisfied with it? If you return it, are you required to pay shipping costs or a restocking fee?

Email or call the seller if you have any questions. Don’t place any bids until you get straight and satisfactory answers.

When Bidding
Establish a top price and stick to it. This can help ensure that you get a fair price and protect you from “shill bidding” Don’t bid on an item you don’t intend to buy. If you’re the highest bidder, you’re obligated to follow through with the transaction. Some auction sites bar “non-paying” bidders, also known as “deadbeats,” from future bidding.

Save all transaction information. Print the seller’s identification; the item description; and the time, date and price you bid on the item. Print and save every email you send and receive from the auction company or the seller.

Before Paying
Know and understand what form of payment the seller accepts. If the seller accepts only cashier’s checks or money orders, decide whether you’re willing to risk sending your payment before you receive the product.

Protect your privacy. Never provide your Social Security number, driver’s license number, credit card number, or bank account information until you have checked out the seller and the online payment or escrow service, if you’re using one, to ensure legitimacy.

If the seller insists on using a particular escrow or online payment service you’ve never heard of, check it out. Visit its Web site. A site that is generally of poor quality with, say, misspelled words or claims that the service is affiliated with the government, is suspect. Call the customer service line. If there isn’t one or if you call and can’t reach someone, don’t use the service.

Before you agree to use any online payment or escrow service, read the service’s terms of agreement:

If it’s an online payment service, find out whether it offers buyers any recourse if sellers don’t keep their end of the bargain, whether it prevents sellers from accessing their funds if buyers are not satisfied with the product, and who is responsible for paying for credit card charge backs or transaction reversal requests. If the online payment service cannot recover the loss from the seller, it might try to recover its loss from you, using the credit card or bank account information in its file. To limit your exposure, consider reserving a separate credit card, stored-value card or bank account to use just for online transactions.

Examine the online payment and escrow service’s privacy policy and security measures. Never disclose financial or personal information unless you know why it’s being collected, how it will be used, and how it will be safeguarded.

Be suspicious of an online escrow service that cannot process its own transactions and requires you to set up accounts with online payment services. Legitimate escrow services never do this.

Check with the Better Business Bureau, state attorney general or consumer protection agency — where you live and where the online payment or escrow service is based — to see whether there are any unresolved complaints against the service. Keep in mind that a lack of complaints doesn’t necessarily mean that a service has no problems.