How can you increase your investment return by 20%?

Simple answer use low cost index funds and the facts speak for themselves.

From the N.Y. Times…

In an article last year in Financial Analysts Journal, William F. Sharpe, a Nobel laureate in economics, calculated that owners of the Vanguard Total Stock Market Index fund, a passively managed fund with annual expenses of 0.06 percent, could “look forward to having the funds saved for their retirement provide 20 percent more purchasing power” than owners of actively managed stock funds, with typical expenses of 1.12 percent.