How to build a portfolio?
Not to put all mushrooms in one basket is a long-standing rule of thumb, and it really is the only true one. The market is never static: investors’ interests change, as do the economy, politics, and the epidemiological situation, which affect the price dynamics more than we would like. It's scary to lose everything, and therefore, you should master diversification.
A portfolio may be diversified with the different sectors: for instance, technology, consumer, and energy, as well as with the different instruments: shares, funds and bonds.
Shares are the most profitable portion of your portfolio. This is where you take on the risk of the company's management and its decisions.
Therefore, in order to invest in the company's shares, you have to be aware of the past decisions of the management, profitability of the business, and its performance. Shares go up in price faster, but they can also go down in price pretty fast.
ETFs or funds represent a more moderate risk, but also a moderate yield. Here you don't need to know well about each particular company because you invest in several companies at once. For instance, the SPY is an index fund for the entire S&P 500. Due to such distribution, the risk is reduced.
Bonds are a protective part of the portfolio. In times of high volatility (price spikes), bonds will act as your anchor and will ensure low but stable yield.
Your portfolio should consist of all the stock market instruments. What percentage? It depends on your risk profile.