Trendline is one of the most easiest to understand technical indicators. Most of the charting software will automatically draw the trend line for you. You can use a bullish trendline and the bullish candlestick patterns to pick long entry points as well as confirm trends. In the same manner, you can use a bearish trendline in conjunction with bearish candlestick patterns for a short entry in the market.
When you combine a bullish trendline with a bullish candlestick pattern or a bearish trendline with a bearish candlestick pattern, you will get a pretty accurate signal that tells whether you should stick with a position or exit it.