Warren Buffett has served as the chairman and CEO of investment firm Berkshire Hathaway (BRK.A -0.28%) (BRK.B -0.68%) for 50 years and guided the company to incredible, market-crushing returns along the way. He's seen conditions good and bad and kept a steady hand to post incredible performance through it all. The Oracle of Omaha celebrated his 90th birthday on Aug. 30, entering into his nonagenarian years with the distinction of being one of history's most successful investors.

Counting the recession that the U.S. entered into in April, Buffett has witnessed eight different recessions for the U.S. economy during his tenure as Berkshire's chairman. So who better to turn to for guidance amid the current economic downturn? These three lessons from the famous money man could help investors weather uncertainty and steer their portfolios to big long-term gains. 

Warren Buffett.

Image source: The Motley Fool.

1. Good companies outperform cheap stocks

"It's far better to buy a wonderful company at a fair price than a fair company at a wonderful price." That quote certainly makes the short list of Buffett's most famous distillations of investing wisdom, and it gets to the heart of a stock-picking foundation that's especially important to keep in mind during a recession.

Recessions often have the effect of shaking out struggling businesses. While the stock market has rebounded from its March crash and indexes including the S&P 500 and the Nasdaq have recently hit new highs, there are still weak spots in the economy that investors should be keeping in mind. Unemployment is high, enterprises are pulling back on growth initiatives, and consumer confidence has been shaken amid pressures brought on by COVID-19 and the current recession.

Investors should be prioritizing stocks backed by strong businesses with sustainable competitive advantages. It's easy to look at a company's valuation and fixate on the appeal of low earnings, sales, or price-to-book multiples, but these indicators can be misleading if the underlying business is on an irreversible downtrend. Buffett is famous for being a value investor, but identifying quality businesses has almost always been Berkshire's starting point in identifying stocks with attractive valuations.

Look for great deals, but make sure that you focus your search on great companies.

2. Tough times can actually be great times to buy

A willingness to buy aggressively during sell-offs has been a defining factor in Buffett and Berkshire's market-crushing success. As the Oracle of Omaha once said: "Bad news is an investor's best friend. It lets you buy a slice of America's future at a marked-down price."

Investors aren't wrong to survey the current recession, market pressures related to the coronavirus, and other headline-worthy stressors and see catalysts for potential volatility. On the other hand, U.S. industry still looks pretty strong, and downturns have historically presented attractive buying opportunities for stocks. To use another Buffett maxim, sometimes it pays to be greedy when others are fearful. 

Of course, investors have to keep some differentiating factors about the current recession in mind. Unlike previous recessions in which economic downturns corresponded with a significant and prolonged downturn for the stocks, the market has been remarkably resilient this year.

While coronavirus-related concerns prompted dramatic sell-offs for the market in March, the subsequent recovery transpired at a record pace. Investors should avoid pouring into stocks where it looks like the market is getting greedy, but the current recession should continue to present worthwhile opportunities to build long-term stakes in strong companies. There's a good chance that this year's trading will continue to be defined by volatile swings, and that could present opportunities to build positions in stocks with strong prospects and underappreciated outlooks. 

3. Take a long-term approach to investing

Buffett has famously said that his favorite period to hold a stock is forever. Focusing on stocks that are primed for success over the ultra-long term will encourage you to consider a greater range of potential outcomes and apply stricter criteria for your investments. A buy-to-hold approach will also prevent you from missing out on a stock's best days and put you in a position to benefit from momentum for the broader market. 

Buffett is famous for beating the performance of the S&P 500 index, but he's also a big proponent of investing in funds that track the index because of his belief in the market as a vehicle for long-term wealth creation.

If you had invested in the SPDR S&P 500 ETF and held over the last decade, you would have enjoyed total returns of more than 300%. If you held the fund for 30 years, you would have seen returns of more than 1,150%. Meanwhile, Berkshire's Class A stock delivered a total return of more than 2,400% across the same stretch. Even relatively conservative investments can deliver big returns if you're willing to be patient and let the passage of time work in your favor.