Michael Martin is a trader and instructor. His show deals with the emotional and psychological aspects of trading and managing risk. His book "The Inner Voice of Trading" and features interviews with Michael Marcus, Bill Dunn, and Ed Seykota - who also wrote the Foreword. Get the audio book free at MartinKronicle.com.
If the instrument you're looking at has a daily volatility measurement that is greater in dollars than you are willing to risk, you must pass on the trade.