how do you diversify your portfolio

I am often asked by people: how do you diversify your portfolio.

Here is my answer:

Diversify your investment portfolio only when you master one of investment vehicle. People who have no idea what they are doing diversify endlessly. They end in very average or poor return because they simply want to avoid risk. Particular for young people, with the limited time, energy, effort and funding, you should focus on one investment strategy, master on it before you move to next one (diversification).