Warren Buffett took over Berkshire Hathaway in 1965. At the time, the company was a struggling textile mill in New Bedford, Mass. Today, the investing conglomerate has a market cap of more than $500 billion and the 88-year-old CEO and chairman is himself worth $87 billion, according to Bloomberg's Billionaire Index.

Each year, Buffett writes a letter to his shareholders. Here are five pieces of Buffett's best advice about to be successful in business, culled from early annual letters.