Some of the best-known billionaire investors follow one common approach: They are value investors. People like Warren Buffett, CEO of Berkshire Hathaway (ticker: BRK.A, BRK.B); Seth Klarman, CEO and portfolio manager of Baupost Group; Mason Hawkins, founder of Southeastern Asset Management; and Mario Gabelli, CEO of GAMCO Investors (GBL), are a few value investors. They may have taken different paths to make their fortunes, but there are similarities in their value investing strategies, says Trip Miller, founder and managing partner of Gullane Capital Partners.