I was watching one of the poker professionals on the television and he said, "I would never risk my family (i.e., his entire stake in the tournament)unless he was sure he had the absolute best hand possible." And I think this is one of the big differences between professionals and amateurs. Amateurs will see a high pair and risk everything on it, not realizing that they have about a 20-30% chance of surviving if everyone at the table were to call. Some of my biggest disasters happen when I get QQ and when the first three cards are shown, perhaps I see J, 6, and 3 -- all of different suits. At that point, I might be willing to go all in with my hand. However, what could still beat me at that time (AA, KK, and a pocket JJ, 66, or 33). So that's five better hands than mine -- its not the best hand and that's why about 20-30% of the time I get really hurt by it.

You really need to think about what's out there (in poker or the market) that could really hurt you.