when you price is start falling then you don't need to take tension but you need to be happy. you must start buying coins at that time more and more and when the price again start increasing then you need to start selling coins with time. so in this way you will get much profit and it is the best way of trading.
it depends upon the situation if the price is bigger then you need to exchange your bitcoin into foat before that happens. Im a trader since then and i sont want to lose any piece of bitcoin and having trouble with the profit i get so i manage to buy and sell since im from in the 3rd world country where we can easily exchange fiat into bitcoin.