When shares start going the wrong way, take the pain and rip it off in one motion like a bandaid. Of course, every investment will wobble a tiny bit in value, but if the stock falls through you pre-determined loss-limit, it's possibly time to take the hit and move on.
Often the shares will just keep sinking, making the early exciters look pretty smart. This also opens up the opportunity to buy back in at much lower levels in the near future.