For investors, a useful exercise is to visualize who's on the other side of whatever trade you're making. If you're buying, that means someone else is selling. What are their motivations? What information do they have that you don't, and vice versa?
That's a valuable thought process if you're a stock investor: You might naturally assume that your case for buying or selling something is airtight. Thinking through the opposite thesis can help identify risk factors and set expectations. It can keep you from falling into the confirmation bias trap.