For me I would stick to holding when prices drops. I believe that there is just no point in selling my holdings of I can't earn any profit out of it. I never give in to fear and go panic selling like everyone else does. If I have also the resources I would buy bitcoins during price drops for they are mostly cheap and add them to my holdings.
Well you can always short what you are holding if you think that it will still fall down, by doing so you have the chance of buying what you have been holding for a cheaper price therefore getting more quantity out of it. Another way to earn while the orices are falling down is of course exchanging what you are holding to another cryptocurrency, with this way you are looking for an altcoin where its falling faster than what you are holding. The greater the price dominance of what you are holding to what you will buy the bigger you will get in return.