The key to suspense in a great story is to give the audience just enough hope, just enough insight, and just enough plot to keep them satisfied, but extremely hungry. It has been said that it's difficult for a poor actor to ruin a great script, but that an amazing actor can have his career destroyed by a poor script.
Giving the audience little hope for the protagonist's situation may work for climatic moments, but like adrenalin, too little hope may have the audience thinking a plot is just too unrealistic when suddenly everything is resolved as if by some wave of the hand.
On the other hand, too much confidence in the outcome may bore the audience. The tantalizing writer will wisely walk the audience across a storyline, like a seasoned tight rope enthusiast, that balances hope against fear. This battle between consonance and dissonance is what drives forward the tale.
Introducing terror that motivates the protagonist allows for later triumph to be experienced when the protagonist overcomes the enormous horrors that faced him. Allowing for anxiety and uncertainty in the protagonist's life prepares the path for the peace and satisfaction that the protagonist, and the audience via empathy, experiences further down the path of the script. Introducing great conflicts and obstacles into the script, which the protagonist must intelligently conquer, creates the ecstasy that one would expect in a motion picture with big dollars behind it. I say "intelligently conquer", because too often the way the protagonist solves or works through a particular challenge can actually make or break a script.
Audiences hate cliched and thoughtless resolutions to challenges such as a protagonist finding keys in his prison cell that somehow accidentally fell off the guard who served him food. This is what most would call a truly unbelievable, and even goofy plot resolution. I would call it downright 'hokey'. Audiences also hate protagonists bypassing plot challenges through impossible, improbable or outright ridiculous methods, such as a protagonist outrunning cars while being chased by helicopters, which he easily shoots from sky, before jumping from the top of a downtown corporate building into a fountain that is eight stories below to escape the thugs. Perhaps this would work in a comedy, but in a serious drama, such a display of the surreal will lose credibility with the audience, who will now wonder if a clown will be shot from a cannon to end the bad guys in the finale.
Using unrealistic or cliched resolutions or not having any obstacles or challenges to overcome can destroy any script. Therefore, one of the most difficult jobs for a great scriptwriter is to create many tough challenges for the protagonist, including a few impossible ones near the climax, while exercising their minds and taking the time to build out well-developed, highly intelligent resolutions to the roadblocks they create for the protagonist. This is just hard work that can't be side-stepped if a writer expects to take his audience on a journey, and every audience loves the adventure, the thrill of the road trip that carries them from the start of a script to its ending. It's why they watch. And the more original the devised methods of the protagonist to overcome his fears and foes, the more the audience loves the movie.
Too much information can give away the rest of the story, in which case if the viewer is like me, I'd rather just turn off the movie and do something else once I know the ending of the plot. Paul Harvey, the radio editorial genius, made an entire radio syndication series based upon suspense. Many writers have made a name for themselves based upon suspense alone.
Too little insight, on the other hand, can leave the audience confused as to what has happened, what is happening, and therefore uncaring or completely apathetic regarding what is about to happen. A writer must be clear as the focal point of a movie camera lens, but as mysterious as an illusionist in what he allows the audience to see. Distraction, plot twists, and detours are all enjoyable to any great adventure, and movies are all about the adventure. Sometimes the adventure has the protagonist exploring love, life, danger, or an important mission, but all adventures are based upon how well conflict and resolution are pitted against each other.
Every important work is always based upon a great theme, a theme universally important to a large audience, such as the survival of the human race or seeing thousands of people saved from a terrorist attack or experiencing the life of a dog whose life is saved after it was close to dying at the hands of some cruel individual. As a general rule, the more universal the desired goal of the protagonist is, the larger the audience for the movie; the more important the theme of the movie, the more interesting the movie is to the audience such as a movie about national security, instead of a movie about a family of seals who migrate to their new home. A great theme must also include a lesson of morality to the audience in which both the protagonist and the audience experience transformation that inspires them in their lives and bring them to a a more spiritual place. This is why movies that move people toward their more base desires seldom get great reviews or do well in the box office. Greatness is measured in both the spiritual and the physical satisfaction and progress that the protagonist and the audience feel they have achieved at the end of the movie.
The moments in a film that must be told, but which aren't quite as exciting, should be told quickly, perhaps as an ellipsis or in a quick but authentic flurry of images, much like a poker expert flipping through an array of cards for an unsuspecting viewer who is about to choose a card from the deck. The meaty, tasty bits of the movie's plot, full of all the angst, pathos and fear of the unknown that delights the audience, should be slowed down to the point that such a moment brings the viewer to the edge of their seat in agony, awaiting the next second of uncertainty with breathless anticipation. These moments of juicy emotional suspense should be slowly drawn out much like a steak connoisseur enjoying each morsel of a filet mignon.
And sometimes the moment that really catches you off-guard is when the current emotional state of the actors in a scene show them trudging through a normal and rather dull, eventless day of life, when suddenly from nowhere, a traumatic event jolts them from their mediocre, complacent existence into a waterfall of activity as they are blindsided, sometimes literally. Then a driving flurried avalanche of one event after another clutches the protagonist in an iron-like chokehold and like a roller coaster ride, which never lets you free from its relentless grip, you are transfixed on the edge of your seat, gaping at the passing events unfolding before you until the ride comes to a complete stop with the thrilling climax. This rush, which we call the 'thrill of the hunt', draws you deep into the plot until all thoughts of life around you fade into the background as you are seized with the passion of the protagonist to accomplish this most important universal desire, an objective so dear to the audience that they dare not leave the room to get their munchies from the kitchen until the flurry of plot twists has ended.
This is just one very good reason that I'm always willing to WAIT. FOR. IT.