This the strategy for 3 Supertrend indicator, here is how it work:
buy : only buy if there is 2 supertrend with green line color, exit when there is 2 supertrend with red line color
sell : only sell if there is 2 supertrend with red line color, exit when there is 2 supertrend with green line color
it can apply to any timeframe except 1minute timeframe .