There is no such thing to learn, it was very simple to trade, investing and selling your coins at the right time will make you earn a huge amount of profit in the market.
Everyone here knows that but nobody can predict the time to buy and time to sell. But if you want to get an idea of when the market is going to drop look for the possible FUD in the market and also if the weekend is approaching then a dump may happen soon. Again since last year there was a massive bullrun in December this year also people are looking forward to such a bull run.
On social media you may see a lot of people blabbering about the end of crypto and all - they are just spreading FUD. Take you own decisions and be firm to them. Sell when you need to and buy when you see its a dip.