Or just buy more at the dip;)
Personally, I prefer to never sell. Of course, I see that a lot of times, selling would be the wisest move, but then again, you have to choose the right time to buy back in. With all the ICO's happening in 2018, Ethereum is in constant demand, so even though there might be a correction, I'm sure the growth will be positive in the long run, regardless.
Cheers.