4) And lastly, Don't Invest more than you can afford to loose.
I think that the 4th advice was a good advice in 2011-2017. Today Bitcoin's price is very high, the market cap is already saturated and by investing a small amount of money, you are going nowhere because a tiny profit won't do much to a tiny budget. Today there are many reasons to be confident and invest more than you can afford to lose. One of the reason is the fact that governments, states and companies are creating Bitcoin strategic reserves and they are investing into it.
Nothing has changed since then, and this principle applies equally to everything where you invest your money. If you invest more than you can afford to lose, then in the event of a negative scenario, your financial stability will collapse and you will become bankrupt. There is no 100% safe investment.