Suspense is a feeling of apprehension and anxiety about the outcome of an event.
Related Articles: Conflict
There are a number of key elements you can use to create suspense.
A "ticking clock" will heighten suspense.
The audience must know something the characters are unaware of, such as the time limit and location of a bomb.
When characters know as much as the audience, often, more conflict is added, such as a bomb's clock starting to tick faster when a character is holding it or cuts wrong wire.
Characters we care about
This doesn't mean they have to be "good guys", but you will not achieve suspense if nobody cares about your characters.
This is why action scenes at the start of a novel can sometimes be ineffective, unless the protaganist is fleshed out before or during the action.
The audience must believe that the worst outcome can occur. Suspense won't be achieved if the reader feels there is only a small chance of the worst occuring.
This may require showing the worst outcome in an earlier scene.
- "There is a clear difference between surprise and suspense […]. We are sitting here and having an innocent conversation. Let us assume that there is a bomb under this table between us. […] suddenly there is a loud boom and the bomb goes off. The audience is surprised, but before this surprise they have only seen a very ordinary scene without any significance. Let us instead look at a suspense scene. The bomb is under the table and the audience is aware of this because they have seen the anarchist plant it there. They also know that the bomb will go off at one o’clock, and up on the wall is a clock showing that the time is now quarter to one […]. In the first scene we have given the audience 15 seconds of surprise […] but in the last scene we have given them fifteen minutes of suspense." - Alfred Hitchcock