The rules is very simple . Buy low , sell high . Also when you bought a coin for a price , and that coin is going down , you should wait until is going back at the original price and sell that coin 
I agreed! this is pretty basic, every body should know this by now if you're into trading. You should only hold if the original price of your Bitcoin is down. You can sell them in the perfect time when Bitcoin is gaining more value. Its up to you when is your comfortable pricing for your bitcoins to sell. If you follow this algorithm you can always succeed in the trading industry but it's not that easy my friend
