It is asked so much but there is only answer for me: hodl! you can do something else as well but the best way to survive is hodling. Sometimes even hodling may not be useful, you must lose everything to come back stronger sometimes 
One should have market research, gather all possible information about the coin you are planning to invest, and you must have a lot of Patient specially during the time when the market is dropping, hold on and monitor the market movement, it may take time for one coin to to go up again after the market glitz, but market will correct itself then stabilized to the favorable status. always remember that the market is Volatile, anything can happened at any given time.