A lot of depends on potential of the coin and how useful it is.
Cryptocurrency is very volatile. It is good for trading.
But for long term investment coin must be useful.
It is necessary to evaluate the future potential of the coin.
Now there is a big demand in nature protection, that is why the project that protects the planet from pollution like this
https://twitter.com/liquidearth_nft/status/1502269439785541633 has a good potential for investment.
It is necessary to sell the coin when its price rise to have the maximum profit from investment.
But when market falls it necessary to buy coins.
But not all coins will be able to survive during fall of the market. That is why it is important to evaluate the future potential of the coin.
Usually when market rise a lot of people buy coins because they want to have maximum profit.
They buy more and more. And when market fall they do not believe in it.
They thing that it is just a temporary correction and market will continue to grow.