British makeup artist Lisa Eldridge calls celebs like Cameron Diaz and Katy Perry her clients and has styled fashion shows and magazine covers for 20 years. But the story of how she became a global star began three years ago, with a hangover.

"I had a bad hangover and thought, I'll make a video today because I look so awful," Eldridge, a 20-year veteran of the makeup industry, who declined to give her age, told ABCNews.com. "It was called 'Morning After Makeup' and there was a part one and a part two."

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Those two videos, in which Eldridge, using herself as the subject, gave detailed tutorials on how to use makeup to perk up your skin and face after a long night, became the basis for what could be called Eldridge's second career as a YouTube star.

After those videos received thousands of views and comments, Eldridge began to create similar tutorial videos weekly, posting them on her website, LisaEldridge.com.

Three years later Eldridge has done hundreds of videos, each with a specific, and often cheeky, topic that reflects her philosophy on makeup.

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Her "Meeting the Ex" video, for example, was inspired by a supermodel client nervous about looking just right for a possible encounter with a former beau.

"I thought, I have to make a film about this because even supermodels have this problem," Eldridge said.

Eldridge's other most popular videos include ones in which she demonstrates how to recreate the looks of famous movie stars - like Audrey Hepburn in "Breakfast at Tiffany's" and Kate Winslet's red carpet look - and more practical topics like her own beauty regime on long flights and how to achieve a "no makeup" look with makeup.

"I saw that there were loads of amateurs doing makeup on YouTube and there was no one like me, of my level, doing tutorials," Eldridge said. "There was a gap in the market and this was a way to answer all the questions."

The most recent video series for Eldridge, who counts one of the world's biggest collections of vintage makeup to her name, focuses on finding the perfect foundation, something that she says reflects her No. 1 makeup tip for women of all ages.

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"Foundation is the most important," she said. "If you can crack your skin care and skin type and really find a foundation that you can rely on and walk out of the house with really great skin, then everything else is a bonus."

"If you haven't got the basics right, the purple eye shadow is never going to look that great," she said of the industry's typical approach of selling the latest trend.

Eldridge also believes that same philosophy of hers to not fall into fads - plus she doesn't advertise or act as a paid spokesperson for items she uses in her videos - is why she has developed such a loyal following, 40 million video views and counting, online.

"Everything has been word of mouth," Eldridge said. "It's like a girl chat. When I go out, people think they know me as a girlfriend from the videos and that's what I want."

"I'm an expert but I'm chatting with you and this is what I know," she said of her approach.

Interestingly, that approach seems to appeal most to American women who, despite Eldridge's London-based operation, represent 52 percent of the traffic to her website.

"I can't explain that," she said. "I don't really know why."