In 1936, Dale Carnegie wrote one of the world’s most popular self help books - How to Win Friends and Influence People.The idea was suggested by a book editor who had attended one of Dale’s public speaking courses in New York.The result was a mix of psychology, philosophy and good old-fashioned common sense. Dale offered advice like: Smile. Give praise. Be a good listener. And remember people’s names. The book went on to become a best seller. Today, more than 30 million copies have been sold worldwide, and it has been translated into 36 languages. Even the title is part of popular culture.Dale’s daughter Donna Dale Carnegie tells Jane Wilkinson about the secret of its success.(Photo: How to Win Friends and Influence People in 1955. Credit: Frederic Hamilton/Hulton Archive/Getty Images)