Advice from Buffett's 30-year-old right-hand woman

Warren Buffett's son Howard isn't the only trusted lieutenant of the Berkshire Hathaway brand who can run a big business with a middle American farmer's mind-set.

Tracy Britt Cool, 30 and just named CEO of wholly owned Berkshire Hathaway subsidiary Pampered Chef, began her journey to the Oracle of Omaha from a childhood on a fruit-and-vegetable farm in Manhattan, Kansas.

"At around 10 years of age, I had my own farmer's market stand," recalled Cool, speaking with CNBC in Boston last month, after being named a member of the CNBC NEXT List. (Buffett's stock market investing lieutenants Todd Combs and Ted Weschler also made the CNBC NEXT List.)

"I hired my friends and set their wages, set the prices of fruit and vegetables, and I realized I liked all those aspects of business and that's what I wanted to go into," Cool said.

Tracy Britt Cool
Lacy O'Toole | CNBC
"You need to learn every single day, and if you don't go to bed smarter than you woke up, it really wasn't a productive day." -Tracy Britt Cool, Pampered Chef CEO

In 2009, Cool graduated from Harvard Business School and contacted Buffett (whom she first met in 2006) offering to be a "gal Friday" of sorts in Omaha if he agreed to let her pick his brain on investment and business topics. Buffett ended up creating a role for Cool to join Berkshire a few weeks after what was expected to be a temporary visit, and after she had already accepted her first post-business school offer with another company.

Now, in addition to running Pampered Chef, Cool is a board member at Heinz, Benjamin Moore and Johns Manville—among her many duties helping to oversee Berkshire's sprawling investments and subsidiaries.

Cool has been able to bottom line what it takes to succeed and what it will take in the future, in the straightforward speak associated with her mentor.

What makes for the best companies?
"The best companies are the ones where there is a great combination of team and talent, and then you have a product or a service that is really necessary for the long term," she said.

What is the best way for a company to learn?
"The primary advice I give to companies is to try to learn from those outside your own business. There's lots of knowledge within a business, with an industry, but I think there's lots of learning that can come from other companies. You need to learn every single day, and if you don't go to bed smarter than you woke up, it really wasn't a productive day."

What will define the future of business?
"Over the next 25 years, technology is going to be a critical component of business, and not just traditional IT and fulfillment centers, but it's the whole customer experience and personalization and tools that companies can offer to help improve the customer experience. I'm very excited about the future. There will be lots of changes, new businesses and businesses disrupting existing business ... tremendous opportunity to work across borders. ... It makes sense, given a global population, we're more connected now than we've ever been. ... It will be amazing to watch what unfolds."

And in Cool's case, maybe watching as the next CEO of Berkshire Hathaway?