Making mistakes is never fun. And this is particularly true when it comes to investing, as money is on the line. It's for this reason that many of us often refuse to learn from our mistakes, choosing instead to erase painful experiences from our memories.

With this in mind, Motley Fool contributor John Maxfield discusses the three most important lessons that investors never seem to learn. In doing so, he provides a simple strategy, centered around the Vanguard Total  Stock Market Return ETF (NYSEMKT:VTI) and the SPDR S&P 500 (NYSEMKT:SPY) ETF, to help combat these emotional and behavioral errors.

John Maxfield and The Motley Fool have no position in any stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.