It's simple, but not easy

[An education in] investing requires only two courses: How to Value a Business, and How to Think About Markets. You don't have to know how to value all businesses. Start with a small circle of competence, things you can understand. [Look for] things that are selling for less than they're worth. Forget about things you can't understand. You need to understand accounting, which has enormous limitations. [You need to] understand when a competitive advantage is durable or fleeting. Learn that the market is there to serve you, not instruct you. In the investing business, if you have an IQ of 150, sell 30 points to someone else. You do not need to be a genius. You need to have emotional stability, inner peace and be able to think for yourself, [since] you're subjected to all sorts of stimuli. It's not a complicated game; you don't need to understand math. It's simple, but not easy.

- Warren Buffett