If story structure could be represented by a line drawn on a sheet of paper it would look like a connected series of zig-zags spun around three or four radical turns at the major plot points. These zig-zags and turns represent surprises of various strengths.
Telegraphing your punches eliminates surprises. It makes your stories predictable – not a good thing. In his book, Film Scriptwriting, Dwight. V Swain reminds us that what we need in our stories is development that is unanticipated but logical. Or, as I often say in my own classes, to have development that is unexpected yet plausible.
One way to achieve this is to set up an anticipated line of action then, in the words of Swain, pull a different rabbit out of the hat.
But you can’t cheat. Surprises must spring from the connective tissue of your story – they can’t feel inauthentic or forced.
Suppose that your hero has encountered numerous obstacles in order to sneak into the room where his girlfriend is supposedly waiting for him. He struggles up along the drainpipe outside the house and finally reaches her open window. The room is in darkness. He climbs inside, and, panting with passion and fatigue, he tiptoes to the figure lying on the bed. The bedside light goes on to reveal that the figure is not his girlfriend but her mother.
This sort of surprise might not necessarily rise to the level of a turning point, but it does constitute a zig-zag in the story’s path. Providing it has been allowed for by your earlier setup, this kind of twist will help keep your story unpredictable.
To keep your stories fresh and unpredictable lead your readers and audiences in one direction then surprise them with plausible but unanticipated twists in another.