Strikingly similar pieces of advice from lots of very successful, financially and otherwise, people in this article. Obviously, that is not a coincidence. I think my favourite quotes from this piece are Jobs, Robbins, and Branson. 

They tie in with my own top tips on how to invest in financial markets: 

1. Diversification is your only 'free lunch': Thus, most people should exercise the 3 D's: diversify, diversify, diversify. 

2. Markets work: So, don't try and time the market, or pick winning stocks. You have to be right twice every time, incur costs, and are competing not only against hundreds of thousands of other investors and experts, but now against the hundreds of billions in computer / high frequency trading that happens daily. You don't need to take the risk because long term markets on aggregate generate 10% gross and 5% real return. 

3. Small and value stocks are a sensible asset class to diversify in. Small and Value stocks average 15% gross per annum (before inflation). If you're looking for higher return and can accept a bit more "up and down", then this is where you should look to, as logic suggests the risk/reward matrix will mean small and value companies provide higher expected returns than their larger, expensive counterparts respectively.