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 very hard to predict the future price of cryptocurrency. That is why it is nearly impossible to find the best time for sell atcoins.
Now cryptocurrency market falls and and it is not the best time to sell tokens and altcoins.
But all altcoins are different and not all altcoins will be able to survive during the fall of the market. That is why it is impossible to give one common advice.
The fall of the market is a good reason to buy tokens. Now a lot of new tokens appear and it is necessary to carefully monitor the market to find the best projects for investment.
You will get the maximum profit if you will invest on the seed or pre-sale stages of token sale.