Not the most accurate indicator, but if combined with some others, it could help you.
BUY Conditions (green):
1. Blue candlestick closes above Bollinger Bands
2. Red candlestick opens outside Bollinger Bands
SELL Conditions (red):
1. Red candlestick closes below Bollinger Bands
2. Blue candlestick opens outside Bollinger Bands
Please always remember, there is no holy grail indicator!