I find that many people have a habit of holding ETH, BTC, altcoin for a long time and always hoping that it will rise again. If you are a trader, you will lose money for that. Set small target and sell them when you see profits. I only need 3-5% profit when trading.
If you see the market going down, stop loss before it's too late. You may lose 5-10% of the capital but when the market goes down you can buy more btc, eth when you hold btc, eth, altcoin.
Sell all ETH, BTC into Stable Coin when the market goes down
Well this is true I have some friends who didn't do this and when the market crash they couldn't do anything but to cry one of them lost almost 70% of his investment.
Back when I was holding some alt-coins I would usually set up a goal when to sell them .