Last weekend I flew to Omaha to be among the 27,000 people congregating to listen to Warren Buffett, the Oracle of Omaha, speak at the annual shareholders meeting for Berkshire Hathaway (NYSE:BRKa) (NYSE:BRKb).

Like other attendees, I wanted to understand what shaped Buffett's career and what advice he had for others who were interested in following a similar path.

Growing rich
Some of his advice is for investors of all ages.

While discussing the importance of learning about investing, Buffett mentioned in passing that by the age of 10, he had read every book on investing in Omaha's public library.

In answering a 10-year-old girl's question about how to earn money (he recommended a paper route when she became a little older), he related having tried about 20 businesses by the time he graduated from high school (apparently the most successful one was a pinball business). Charlie Munger's advice to the little girl was that she become a very reliable person.

Lessons from Davy
In the Berkshire movie, a portrait of Warren Buffett in his early twenties emerged during a part that paid tribute to Lorimer Davidson (also known as Davy), GEICO's former CEO. The initial meeting between Buffett and Davidson was also discussed in the 1995 Berkshire Hathaway chariman's letter.

In 1951, Buffett was studying economics at Columbia Business School under Benjamin Graham. He learned that Graham was chairman of Government Employees Insurance Co., the predecessor to GEICO. So on a cold Saturday, this 20-year-old student took the train to Washington, D.C., and headed to the headquarters, uninvited.

To his surprise, the company doors were locked, but he knocked until a custodian opened the doors. Buffett asked whether there was anyone to talk to, and was told that one man was working that weekend. Buffett introduced himself to Davidson -- then assistant to the president -- as one of Graham's students and asked whether he could ask some questions.

In the movie, Davy recalled how the conversation lasted more than four hours and how the young Buffett asked very detailed, thoughtful questions. Buffett reminisced on what a seminal half-day it was in his life.

Seeing that intelligence, work ethic, and determination at an early age, one can understand how he has become so successful over the years.

Buffett's investing advice
So how would a young Warren invest much more modest sums, say $500,000 to $1 million, was the gist of another question. Buffett said that if he was working with that amount of money, he would do things differently than he is now.

He related that when he was younger, he had more ideas than money -- now he has more money than ideas. Early in his career, Buffett was frequently thinking about which stock to sell to raise money to buy a new stock with better prospects.

He also emphasized how difficult it is to earn extraordinary returns on large amounts of capital and the technical difficulties involved in purchasing huge number of shares without tipping off everyone that Berkshire is buying.

So investors with smaller amounts to invest have some definite advantages over larger investors, assuming that these small investors have solid investment ideas and behave in a rational manner -- particularly during irrational market times.

Giving back
Whenever I fly somewhere, I try to read a book during the flight, so I read Napoleon Hill's Think and Grow Rich, first published in 1937. Andrew Carnegie had given Hill the task of discovering and writing about the money-making secret used by hundreds of millionaires, including Carnegie.

To quote from the preface, "When he saw that I grasped the idea, he asked me if I would be willing to spend 20 years or more preparing myself to take it to the world, to men and women, who without the secret, might go through life as failures. I said I would, and with Mr. Carnegie's cooperation, I have kept my promise."

What was crystal clear at the meeting was that Buffett was thinking something similar. He had grown rich at an early age and was bringing his wisdom to the larger world.

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Fool contributor Michael Cecil is a cardiologist and the author of Drugs for Less: The Complete Guide to Free and Discounted Prescription Drugs. If you would like to discuss the article, email him. Cecil owns shares of Berkshire Hathaway; the Fool has a disclosure policy.