[FabHK]

1. Low costs. Seemingly small fees (such as 1% p.a.) eat up a third of your savings over three decades.

2. Diversify across countries/asset classes. ETFs help. Or adopt a core-satellite strategy (most in some solid cheap broad ETF, a few chunks into more speculative investments.)

3. Be aware of distinction between real/nominal returns (inflation), gross/net returns (fees), total/price returns (dividends).

4. If a bank (or any commission based advisor) recommends it, your first instinct should be: RUN