When I buy it at a low price and it raises to 500%, I think I will sell it.
This is the most common strategy but if the certain Altcoin has a huge potential then i will keep on holding except if i really need the money for my special spending or specially in case of emergencies then i will just sell my Altcoins too but if there is no reason to sell that better to hold it as long as the market performance of my Altcoin is stable.