In my opinion, the second item is incorrect. Typically, the coin price on the crypto-exchange markets drops to -20% and then bounces back to +10% or higher because many investors start buying cheap coins. You need to figure out the current trend of the price movement. If you are sure that the circumstances are negative, sell your crypto-currency immediately. Do not sell coins at low prices if you are in doubt.

My trading strategy is based on scalping, sometimes I use an arbitrage tools. I trade many crypto-currencies simultaneously. I often follow the news from the teams of the coins that I bought.