Anytime you have a breakout from consolidation and a new trend, you like to see volume and a nice green candlestick bar at the breakout. This indicates momentum and will push prices higher.
However, one when a tall green candlestick bar appears at the end of a trend, this is usually a clue that a top is in place. You can then look for a reversal and a short opportunity. If you are in a position and see a 1-minute wonder (tall green bar) it is usually a good sign to take profits or tighten your stops.
A method to determine if a retracement will fail or not is to look at range expansion in candlesticks as well. If the candlestick on a reversal shows range expansion, this is an early sign of a trend failure. There is momentum and panic in that red bar.
Doji's are key candestick patterns that predict a turn of events. The market is undecided on which direction to go. Tony Crabel descibed the doji as a narrow day or a NR7. A NR7 is a day in which the range is narrower than the previous 6 days. Similar to the idea of contracting bollinger bands, you can expect prices to breakout in either direction.