Trend lines can be used in many different ways in trading , some will prefer the bounce of a trend line others will tend to trade Breakouts either a breakout of a channel or a trend line .. etc . 

The following video is very useful starting with clarifying the difference between being a Reactive or Predictive trader then talking about trend line breakout and what is actually you are doing when you decide to play those kind of trades , after that you will learn a trading technique to confirm a breakout of a trend line referring to the term " Sustained Breakout " with chart example to make sure you got the idea ..