If you want to be able to explain what you did wrong, you need to know how to explain what you did right, and why you did it in the first place. You need to know a good business from a bad one, and you need to be able to determine if a company is underpriced or overpriced. If you can’t do that, then you should find someone who can do it for you, otherwise you are just throwing dice at a craps table where the odds are always stacked against you.
