i decide to sell my altcoins. when i noticed that i have a good and high profit to me. when i realized that the value of my altcoins doesnt rise high more. and lastly i decide to sell my altcoins when i really needed money. even if it low or high when i need it then i sell it.
your step is very precise, you must sell altcoin when it is good price and is in need. holding the coins too long is also not good because at any time the price of coins can drop drastically so when the price has reached the highest point better sold.