Susan and Bill Gearing run a full-time online business out of their Columbia, Md., home selling quilting fabrics and accessories.They are among the 1.3 million sellers who make all or some of their living on eBay, the booming global Web bazaar. (Washington Post / Linda Davidson)

Susan Gearing's home office in Columbia, Md., looks like a fun factory - embroidery machines hum, and shelves are lined with 350 rolls of fabric, including some emblazoned with Elvis, Betty Boop and shirtless cowboys.

But behind the colorful facade lies a grueling, complex Internet retail operation. Every day, Gearing cuts, folds and mails 30 yards of fabric to customers around the world who buy from her online. And each year, her business, SusieCraft, grows bigger and more demanding.

The same is true for Jennifer Canty, a Sterling, Va., entrepreneur who started refurbishing iPods and other gadgets and selling them on eBay three years ago, primarily so she could work from home and care for her infant son. Today, the company she founded, Dyscern, employs 12 people, occupies a 10,000-square-foot warehouse and is projecting $6 million in annual revenue.

As Internet shopping matures and enters its 12th holiday season, veteran eBay sellers are discovering what it takes to make a long-term career out of selling online. Internet sales have become as competitive as traditional retail but compounded by the furious pace of change on the Web.

"You have to have a big range of skills that have to come together," Gearing said.

Gearing, 60, and Canty, 35, are among the 1.3 million sellers who make all or some of their living on eBay, the global bazaar where $12.6 billion worth of merchandise changed hands in the most recent quarter. Both have recruited their husbands to help, but both say it's a fantasy that self-employment is stress-free.

"We joke that it was easier when we worked for other people," Canty said, adding that the initial joy of working for herself morphed into another challenge: "Don't let the business take over your life."

Gearing, who learned to sew at age 12, spends much of her time doing the usual spadework of any retailer, scouting quilt shows and magazines to stay on top of trends. She personally answers more than 100 customer e-mails a day and writes ad copy for each of 500 simultaneous listings - "This lovely set of Moda fabrics is the perfect complement to any winter-themed project."

With help from special software and her husband, Bill Gearing, she also tracks packaging and postage for 50 daily outgoing shipments, all while striving to master the latest tricks of Internet marketing.

"We're talking about a blog, and we're looking at (selling) on Amazon," she said. "And gosh, should we be on YouTube?"

At the same time, Gearing faces a learning curve in deciding whether and how to market her fabric through Google and other search engines. If she decides to buy ads tied to search phrases, which words will customers most likely use when hunting for threads?

After eight years of selling on eBay, Gearing still operates out of her home, with no outside staff. She said her business rings up $15,000 in monthly sales during the busy winter period, generating enough income to match her previous salary as a museum director and to augment her husband's retirement income. But like many eBay sellers who don't want to grow too big, Gearing has resisted hiring the people required to take her sales to the next level.

Many businesses stumble as they grow beyond a part-time hobby and start to require hiring, accounting, financing and office space, said Jonathan Garriss, executive director of the Professional eBay Sellers Alliance, a 1,000-member group.

"The traditional pain-points that you see with (online sellers) very much mirror the pain-points of a traditional business," said Garriss, who runs an Internet-based shoe business, Gotham City Online.

"I think there's a pretty big failure rate of businesses on eBay, but they don't account for them."

About 56 percent of all small businesses with employees fail within four years, according to the Small Business Administration. Comparable figures do not exist for Internet businesses, and eBay does not disclose failure rates of its sellers, but experts say success is as elusive online as offline.

"EBay makes it vastly easier to set up your business, but beyond that, normal business rules apply," said Bill Frischling, Canty's husband, who left his job at AOL in 2004 to join his wife at Dyscern.

"And we've seen other businesses implode, ramping up to a point they couldn't manage."

One veteran online seller of movies and music, Glacier Bay DVD, staffed up rapidly after starting on eBay in April 2002. Within two years, it was selling $480,000 worth of goods at auction each month, according to founder Randy Smythe. But shortly after hitting its peak, Glacier Bay DVD fell into the red and eventually became "NARU" on eBay, meaning "not a registered user." Smythe said his business was squeezed by new competition and steady increases in eBay's listing fees.

"I didn't pay enough attention to what was going on," he said.

In order to survive without outside help, especially as eBay draws in many new sellers every year, veteran dealers say they must learn the art of serial reinvention - a hallmark of many successful businesses.

Success with online auctions often requires finding new ways to stay ahead of rivals and boost profits, altering inventory to match demand, or handling more volume while keeping costs down.

"You have to constantly look for new opportunities and new things," said Paul Dholakia, an associate professor at Rice University who studies user behavior on eBay.