She's the most successful self-made female billionaire in the world, and comparatively few people have ever heard of her. Meet Zhou Qunfei, school dropout (by economic necessity), former factory worker--and founder and CEO of Lens Technologies, the world's leading manufacturer of touch screens for companies like Apple and Samsung.

Zhou, 45, who grew up in a tiny village in China, lost her mother at age 5. Her father was nearly blind after an industrial accident. She dropped out of school at age 16, rose through the ranks at work, and ultimately launched her own glass-refining company, which went public earlier this year.

Zhou has a pretty low profile for a woman with a fortune estimated at between $7 billion and $10 billion, but she was profiled recently in both The South China Morning Post and The New York Times.

Here are some of the keys to her success.

1. She refused to accept less than she wanted.

Zhou did well in school, but she had little choice but to set aside her dreams of becoming a fashion designer. Instead, she dropped out at age 16, to go to work in a factory, "making watch lenses for about $1 a day," according to the Times. It was hard work:

I worked from 8 a.m. to 12 a.m., and sometimes until 2 a.m. There were no shifts, just a few dozen people, and we all polished glass. I didn't enjoy it.

Despite the fact that she needed the work and that there were many others lining up to replace her, Zhou wrote to her boss after only three months, thanking him for the opportunity but saying it wasn't enough for her. Instead of letting her go, her boss promoted her. This brave move turned out to be step one on her long road to immense wealth.

2. She thoroughly understood her business.

Because she'd started on the factory floor and risen through the ranks at her first employer, Zhou thoroughly understood every step of the lens-manufacturing process before she launched her own company. Even now, with a work force reported at between 60,000 and 80,000 employees, she's known for walking through her factories and paying close attention to process.

"She'll sometimes sit down and work as an operator to see if there's anything wrong with the process," one of her general managers told the Times. "That will put me in a very awkward position. If there's a problem, she'll say, 'Why didn't you see that?'"

3. She bet on herself again and again.

Zhou left her factory job to launch her own manufacturing firm with a total of $3,000 that she and relatives had saved. This was the first of 11 business she started, according to the SCMP, most of which ultimately failed.

"Twice I had to sell my house to pay my employees' salary," she said.

In fact, it wasn't until 2003 that she had the opportunity to really make her company successful, which leads us to--

4. She said yes to opportunity.

Zhou's expertise was in manufacturing glass lenses for watches, but it was the rise of the newest generations of smart phones that really enabled her success. In 2003, she was contacted by executives from a major mobile phone company, asking whether she'd be willing to retool her company to make screens for phones.

(The timing on this is a actually a little unclear; the Times says it was Motorola in 2003; the SCMP says it was China's TCL Corporation in 2001. Regardless, Zhou jumped at the chance.)

"I got this call, and they said, 'Just answer yes or no, and if the answer's yes, we'll help you set up the process,'" the Times quoted her as saying. "I said yes."

5. She worked incredibly hard.

There's a saying in the Hunan dialect that describes Zhou, her cousin (who serves on her company's board) told the Times: ba de man. It means "a person who dares to do what others are afraid to do."

Yet Zhou apparently demonstrates a rare combination of initiative and diligence. The Times described her work habits as "lean[ing] toward the obsessive."

Her company's headquarters is at one of her manufacturing plants in Changsha. In her spacious office, a door behind her desk opens into a small apartment, ensuring she can roam the factory floor day or night.

6. She maintains balance and humility.

Despite her great fortune and success, the Times described her as exuding both "charm and humility," remaining silent during meetings, but commanding attention when she does speak up, and admonishing a subordinate for failing to sit up straight during one meeting.

"I'm not qualified to be a high-profile person," she was quoted as saying in the SCMP. "I think it's important not to get carried away when you are successful--and not to let yourself feel gloomy when times are bad."