Admittedly, public speaking did not come easy to Mr Buffett – aka the Oracle of Omaha. He repeatedly confessed to ‘great trepidation’ when it came to addressing gatherings during his time at college. Taking a Dale Carnegie course changed that for the better. In fact, Mr Buffett’s diploma from the author of How to Win Friends and Influence People is the only plaque displayed at the Omaha office from where he rules the Berkshire Hathaway business empire.