We just need to set our goal so we don't lose opportunity to sell.
I personally, when my target has been reached im gonna sell it with no regret, even though the price rise after i sell i will not regret it because my target already achieved.
It is also ok to adjust the goal frequently. If you get to find out any news or changes in the team or the code, it's important to include it into you considerations. Not necessary to start from zero again with your thought process, but an iteration of your opinion is key to achieving your peace of mind when in fact you decide to take some profit.
One problem I personally see is hesitation. If you hesitate too long and don't develop and execute a plan, you will be left with bad emotions in the end. Better make a clear cut decision and stick with it. Sell 25% or maybe 50% and see the profits you made as a new opportunity for another investment even if you sold too early.
Having some liquidity available yourself is worth a lot. You see some new project but damn it, all you have is tied up in this other project you liked so much and that started losing value yesterday. Now you hope it recovers while you watch the other project gaining traction.
Less emotions more rationality is my credo, but I admit I also had to learn it the hard way.