One of the things you don’t want to do, when you’re creating your antagonist and putting him through his protagonist-thwarting paces, is to end up with yet another instance of the amazing mind-reading teleporting menace.

You know how that one works:  your protagonist is running across country to escape from the monster, or running from room to room in the big old mansion to escape from the serial killer, or dodging about the streets of the big city to evade the hired-gun assassin-spy.  No matter which way he turns or where he goes, however, the bad guy is always right behind him — or, often, is already there waiting for him.

And a lot of the time, if you stand still long enough to think about it, you realize that there’s no way the antagonist could have gotten to that point from where he was standing before, or that he could have known which way the protagonist was going to turn for help, without being able to read minds and teleport.  Which most serial killers and assassin-spies are not, in fact, able to do.  (The jury is still out on monsters.)

There are two main ways to avoid this problem.  One way is to keep your story moving so fast, and so entertainingly, that the reader never has the time or the inclination to stop dead in his or her tracks and ask, “How the hell was he able to do that?”  The other way is by means of careful plotting and meticulous attention to continuity, which may in fact actually involve tricks like drawing charts and making timelines in order to keep track of what your antagonist is doing during those parts of the story when he isn’t on stage.

When you’re done, if you’ve done it right, your reward will be to have the reader never notice all the hard work that you put in.