Any behavior that could easily lead to permanent capital loss should be eliminated entirely. 1) Don't invest in what you don't understand; 2) Don't short sell or use leverage; 3) Don't engage in short-term speculation, thematic trading, or trend trading; 4) Don't invest in purely conceptual companies with no profit or cash flow; 5) Don't participate in complex financial derivatives whose risks cannot be assessed; 6) Don't envy or be jealous of others' short-term high returns. This is roughly the investment approach Buffett described that won't lose money over a long period (5-10 years).