A trader must have the true mindset, namely businessmen. By having a mindest of business people in trading, traders may not speculate excessively in their trading. Must have a good system, strategy or trading plan, because if the trader does not have it, trading is more towards speculation, try luck or gambling. If you already have a system, strategy and trading plan, the trader is required to be consistent and disciplined in applying it all. This discipline and patience can control us in applying our rule trading. Try not to overcome or trading with feelings of emotions, fear and greedy too. Actually not only the biggest mistake, a small mistake that happens a lot if you are underestimated and ignored it can be like a snowball that rolls more growing, because all the details in the business including trading must be truly noticed.