I am worried always when I saw that the price of BTC is going down. But my senior colleagues always told me that hold because it will going back to normal and will rise again. So better have faith in yourself that bitcoin will going up even though it is on fluctuation stage. Also learn to hear those suggestion because it will really helps you to decide.
Holding is the best practice in my opinion. If the price is 5% or 10% down then okey settle with lose but if the price is 50%/60% down then its better to hold. If the coin is a good one then it will bounce back. It does always.