Before you decide to sell or hodl still, first know your coins if it is for long term or short term only. After that, always remember to put a stop loss for you to avoid being a bagholder or getting rekt (wrecked). Also, take time to think what amount of profit you want. Either 10%-50% or maybe if you are confident enough that it will go beyond 100%, it's ok.
Understanding the coin is vital as it can help us in making accurate predictions about the future price. In trading, it is the skill that leads the trader to success. If we talk about bitcoin, then holding it for few more months is the right thing to do. Selling out now will be the worst mistake of his career. Same is the case with some famous altcoins. The longer you hold, the more profits you grab. Selling out is not recommended by me at the moment.