No matter how good the fundamentals of the coin are, if a coin goes more than 100% within 24 hours I absolutely sell them. A classic case of this has been Storm coin, it has already dipped about 50% from its ath after it went crazy just a couple of days ago.
It's never smart to sell all. You should always keep at least 30% regardless of the profit that you could potentially make by selling that 30% also.