Start with an outline. It doesn't have to be a detailed outline, but a numbered outline showing your major plot points is a good idea. The story might change as you go, but having the basic structure will help keep your pacing in place. Pacing in a suspense novel is one of the keys to successful writing.
Introduce story information at carefully planned intervals. Keep readers just ahead of the characters in your novel. You want them to know what might happen to characters in your novel first to create suspense. This style of writing keeps readers leaning forward in their seats as they anticipate the situation your characters are about to enter.
Create realistic characters. Readers won't be anticipating what might happen to characters they don't care about. Characters need strong personalities and traits that make them real on the pages. Your readers should know them well and either love or hate them.
Combine suspense with other genre elements. You can apply suspenseful writing effectively with horror, psychological thrillers and medical thrillers. Suspense also goes hand in hand with novels of mystery, with which it shares many characteristics.
Foreshadow events. This is arguably the most important technique used in writing any kind of suspense story. Foreshadow events by alluding to them in bits of dialog or with visual clues. This gives readers more to anticipate.