Planning your exit is where predetermination comes into play. The most important plans to arrange would be to evaluate where to exit with a profit, where to exit with a loss & where to set a stop order. A look at BTC recent behavior would determine a reasonable objective. Using the most recent price action to determine a price target. For example an idea would be to calculate recent price swings and average them out to get an approximation on your price target.
Knowing when a trade has failed is quickly evident when trading breakouts because the trend reveals itself. After a significant breakout, old resistance levels tend to act as new support levels and old support levels become the new resistance points. This is an important way to determine where to set your stop-loss order with confidence.
If the current BTC price were to enter short term consolidation before a positive breakout, my stop-loss order would be set for approx $3500 allowing for enough wiggle room during minor price fluctuations before my long term goal is achieved. A piece of advice here would be to mention that you should never really give a loss too much room so confidence in your prediction is desired in such a case.
After a position has been taken, use the old support & resistance levels as a line in the sand to close out a losing trade.