Among their many traits, the best stories are unpredictable. Your audience wants to be led along a path with subtle breadcrumbs. In this regard, assume your reader is intelligent enough to recognise your clues. On the other hand, a twist ending will not be appreciated if it lacks any forewarning. You must learn the art of controlling potential energy—like a bow drawn fully taut, your plot must prepare its twist ending with a graduated series of clues.