Definetly long term is the best way to invest in cryptocurrency, i do hold coins almost 3 years and its the best decisions so far. DYOR is the best advice before buying coin and also you should not following hype and stay away from coin which promise you to the moon without any solid reasons.
with a note that we really choose a project that has strong fundamentals and has a good rating on coinmarketcap. if we choose the right coin, the longer we hold it, the greater the chance of profit. but keep in mind that holding on for a long time is not a guarantee that you will get more profit than those who don't hold back. Crypto is full of surprises, no matter how long you hold it in, as long as you get the moment right you will get a lot.
one strategy can't be applied to all coins, so we have to really adjust ourselves which one is the most effective. This takes patience, so never stop learning.