You will read about investing principles that can be used to evaluate your portfolio and immediately implement changes if necessary. Some rules are common sense advice. Some you may have already heard about. And some could definitely cause controversy: Why index funds perform better than most other actively managed funds How diversification can sometimes be a bad idea Why long term, investing in stocks is less risky than in bonds or bills Why it makes sense to stay invested at all times How simple process of stock picking is better than a complex one