If you have followed Tony Vays you probably noticed that he often uses Tom DeMarks TD Sequential for determining when to buy and sell. The TD Indicator can be a good tool to determine when an uptrend or a downtrend is broken. When using the TD indicator a trader will count the bars in a specific pattern and compare them to the previous bars.
There is a good article on Trade Trekker that explains the details of using the TD Indicator, and it's main components. According to the article,
"The TD Sequential has two parts – TD Setup and TD Countdown. The first phase of TD Sequential starts with a TD Setup and is completed with a 9 count. When the 9 count is completed, it is at that point, a price pause, price pullback, or reversal is likely. It is also at that point where TD Sequential starts the second phase with TD Countdown and is completed with a 13 count. When the 13 count is recorded, it is at that point, a price pause, price pullback, or a reversal is likely."
You can read the full article with examples of how to use the TD Indicator at Trade Trekker. Another good resource for learning the TD Indicator is is listed by Christopher Ting, a faculty member at SMU here: http://www.mysmu.edu/faculty/christophert/QF206/Week_05.pdf