2 different parts to consider before you make the decision whether to buy or sell
First, the decision on what companies to invest in. A good way of deciding is to follow the way of the value investor, the likes of Benjamin Graham and Warren Buffett. This can give greater confidence that the companies that you invest in can weather any storms the market creates and emerge victorious.
Second, the decision on when to buy or sell depends on the emotions of the market. Always keep your emotions in control and opposite to the market. As the saying goes, be greedy when others are fearful and be fearful when others are greedy.
Happy trading