Disclaimers: I'm not a financial advisor, nor do I want to become one. What I know may not be much. This is also a very personal topic. Definitely explore different views.
My motivation is to show that you can also think of investing as a practice of finding uncorrelated assets or strategies, rather than predicting returns.
You want to be invested, all the time (in a portfolio).
Earn decent returns with positive-sum games - Alpha vs Beta
Avoiding losses is more important than chasing gains - Risk-adjusted returns
(If you only read one, then choose this👇)
Developing your portfolio intuition - Diversification is the only free lunch
Don't pick individual stocks / assets - There's a reason why index funds work
Investing based on your own taste
Reading financial news
Elements of a Meta-portfolio
I'm in Europe - what do I do?
Where to read more?
Things not covered here