The same goes when the market is going in the opposite direction. We should hold on and don't get too excited to sell because there might be more to come. There are still things that are also important to have other than to have a control. One of it is to become aware if what is going around you, like you need to watch out for the news or on the coin updates so that you will know if what to do before the price of the coin go on that direction you are suspecting.
Another one would be is to have a knowledge because when you are knowledgeable you will know if what are those coins that you must avoid and what are the coins that you should invest in.
That knowledge includes how to conduct market analysis to find out the price that will occur. Some research does need to be done, to predict each coin you want to choose as an investment. Some coins that should be avoided are coins that do not have a clear development, because coins without a clear development will only be trash. Choosing a coin that has real potential must be done with serious research as well as looking at the current list of the best altcoins.