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.
But now it is difficult to predict how the market will move.
Many people thing that cryptocurrency market will rise in the future, but now it only falls.
Very often all the predictions does not come true.
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.