Don’t be too fixated on daily moves in the stock market (from Berkshire letter published in 2014).
Don’t get excited about your investment gains when the market is climbing (1996).
Don’t be distracted by macroeconomic forecasts (2004).
Don’t limit yourself to just one industry (2008).
Don’t get taken by formulas (2009).
Don’t be short on cash when you need it most (2010).
Don’t wager against the U.S. and its economic potential (2015). ...
Advice from the world greatest investor is fine, but how does anybody implement something like the above?
Stripped down to ultimate simplicity, translating the above into action would mean:
Putting 1/3 of your investment money in a Total U.S. Stock Market Index Fund.
Putting 1/3 of your investment money into a Total International Stock Index fund.
Putting 1/3 of you investment money into the Total Bond Market.
The above gets you wide diversification with a mere three funds. It also goes a long way to fulfilling Warren Buffett's advice up above.
And if you contribute money every week, and train yourself to not pay attention or not freak out if you do, you can pile up a lot of money over the course of ten ... twenty ... or thirty years. But always remember the simple advice that's difficult to follow: "Don't just do something, stand there!"