Well everyone in trading have at least made this mistake once,so you have to learn from this experience and try to not make the same mistake.Next time,you should research the coin that you want to invest,like the news of future update
Actually, I wouldn't call it a mistake because every cryptoholders lost some amount of his capital when cryptos dropped. But all should understand that it is normal on the cryptocurrency market. I believe that cryptos are long-run investments at this stage for most investors so it is better to invest just free money and just take it easy.