Plot twists are unexpected elements or events that not only take the audience by surprise but also increase a novel's suspense. Jeffrey S. Savage's novel, "Dead on Arrival," illustrates this technique very well.
First off--and that's just it--first off, right on page 6, Savage begins with a twist: an odd character, Pinky, tells the protagonist, Shandra Covington, his dead wife is trying to kill him. Then, on page 8, Pinky tells her he's dead. Quite a twist! Savage continues to use this "dead on," ploy throughout the rest of the book (leaving a string of bodies along the way, I might add), thereby leaving the reader in a constant state of questioning and guessing. A good thing.
Second, Savage adds twists to his minor story lines, too, as delineated by the fact that Covington's long time, "best" friend, a handsome cop, suddenly becomes engaged to a slinky, and in my opinion, quite suspicious female. Not a good thing, as far as Covington's concerned, but a very good thing for increasing tension and conflict within the protagonist. It also, again, leaves the reader questioning. Will he really go through with the marriage?
Third, Savage takes us on a "who's really who" journey; i.e., one day, Pinky's dead, and the next day he's not. Back and forth, back and forth, until we don't know who Pinky is at all. In fact, he might even be Covington's father. Now that's twisted! And worse, who really is the bad guy? Or is "it" a girl? Only Savages mind can unwind that mess.