If you are talking about the cryptocurrency market then it is hard to predict the market so you cannot accurately know when to sell and when to hold. This is not like the stock market that some traders based on candle sticks or should i say technical analysis. Bitcoin is different it is very volatile, more volatile than the stock market. What i mean by this is that you cannot just simply rely on the news, if there is going to be bad news then price will fall just like in the stocks. What i can suggest is to just put a target price, say if bitcoin falls to X amount you will be buying and if it gets to this amount you will be selling otherwise you will just hold. You'll be making more profit by doing that. Patience gets rewarded my friend.
thats the difference of long term investment or the quick money making,if the opo wanted to make just money without any high profit expectation well i can say that if the price makes over from what he bought so its the time to sell.but if he really wanted to make good profit he must be willing to wait and it comes for long term biput the earning is surely i credible than what he expected.so better he decide for what he wanted