Depends on the amount you hold and if you have to pay Tax - if you hold a lot and cash out all at once expect a big bill I was speaking to the founder of Monetha and their method was interesting - after their ICO, they cashed 35% of the holding to pay for dev etc, and then every 2 weeks thereafter they cash out a little more.

Its an organised Exit

Personally, if the greed doesn't take hold, I try and cash out the gain to realise it and leave the initial investment in.