found this -
When asked by Jack Schwager what is the one act most traders must do to become successful, Bruce Kovner - perhaps the greatest hedge fund manager ever and a man who has beaten the markets for more than 30 years and to whom other hedge fund managers entrust their savings - simply said," Undertrade, undertrade, undertrade." Prodded further by Schwager, he explained, "Whatever you think your position ought to be, cut it at least in half. My experience with novice traders is that they trade three to five times too big. They are taking five- to ten-percent risks on a trade when they should be risking one- to two-percent."
Unfortunately, this is the advice most retail traders roundly ignore. It's not exciting to trade for pennies and nickels - far more glamorous to try to make $1,000 a day. Yet that is the likeliest path to ruin. After having watched thousands of accounts trade, I can unequivocally say that the biggest reason for the failure of most retail traders is not lack of knowledge, nor is it the inability to understand the nuances of the market or poor technical analysis skills. The number one reason is over-leverage.
