Stocks have done exceptionally well over the last few years. But the scars of the 2008 crash are still making many investors question their long-held beliefs, including the virtues of ‘buy & hold' investing. This shows up in weak money flows into equity mutual funds, which have yet to fully reverse despite the market's strong gains in recent years. On top of this are claims from purveyors of market timing who never tire of reminding us that this investment strategy is no longer relevant to the current uncertain environment.

But long-term investing, particularly a ‘buy & hold' approach, remains as relevant today as it ever has been. And notwithstanding naysayers' claims to the contrary, empirical evidence continues to show the long-term superiority of a ‘buy & hold' strategy over any other investing approach.

But to adequately benefit from this tested and proven strategy, investors need to guard against three major pitfalls. Here they are:

1) ‘Buy & Hold' Doesn't Mean ‘Buy & Forget'

Staying engaged with your portfolio is a must. Investing for the long run doesn't mean that you lose sight of developments in your portfolio. The ‘buy & forget' mantra is a simplified take on the typically long holding horizons of investment icons such as Warren Buffett.

Buffett may be in the habit of keeping his investments for the long term, but he stays fully tuned into what's happening in each of his holdings. While the Oracle of Omaha is no doubt one of the most successful and famous exponents of the ‘buy & hold' investing approach, he is by no means the only one. All of the successful practitioners of this approach stay well informed of what is going on with each of their holdings.

2) Don't Fall for the ‘Buy What You Know' Mantra

Guard against the simplistic beauty of the ‘buy what you know' mantra; another one of those skin-deep lessons learned from Warren Buffett's investment style.