Do not be greedy - There are many people who suffered from being greedy, they tend to spend all their money because of thinking that they could still make more money but instead of earning they have lost their money. ALWAYS KNOW WHEN TO STOP AND CONTINUE TO TRADE.
This is one of the worst kind of emotion that I have seen for some traders. They still keep on spending their money eventhough they already have made big losses.Hoping that they can make a good amount and get their money back.
A professional trader never act like this because they know how to control their emotions.They know how to cut their losses when having a bad trade.
The challenge some traders are facing is to control not to be greedy and some don't even know if they are greedy. After trading and their was lose in the trade, some trader would want to recover the money that was lost by all means, doing this sometimes may not be with a clear mind, but a mind that is very emotional. Being too greedy can make a trader loss a reasonable amount of money.