When I was growing up in Germany, my father pushed me hard to become fluent in English. "No matter what you are going to do," he told me, "this will give you an edge. The English language is the operating system of the free world."
As for worst advice, a Harvard Business School professor encouraged me to display more independence and contrarianism in job interviews: "Firms that hire here," he told me, "don't want yes men." At my interview with a top-tier consulting company, I suggested that the firm might be heading for a decline in market share and prestige. Needless to say, no consulting career for me! Was it bad advice or overzealous execution? NEXT: Tony Robbins