Plot grows out of character. If you focus on who the people in your story are, if you sit and write about two people you know and are getting to know better day by day, something is bound to happen.
I plot as I go. Many novelists write an outline that has almost as many pages as their ultimate book. Others knock out a brief synopsis. . . . Do what is comfortable. If you have to plot out every move your characters make, so be it. Just make sure there is a plausible purpose behind their machinations. A good reader can smell a phony plot a block away.
Any fiction should be a story. In any story there are three elements: persons, a situation, and the fact that in the end something has changed. If nothing has changed, it isn’t a story.
In nearly all good fiction, the basic--all but inescapable--plot form is: A central character wants something, goes after it despite opposition (perhaps including his own doubts), and so arrives at a win, lose, or draw.
The story of a play must be a conflict, and specifically, a conflict between the forces of good and evil within a single person. The good and evil to be defined, of course, as the audience wants to see them.
Sequential causality is generally considered to be very important in plotting. It is often thought to be the difference between a simple story, which just presents events as arranged in their time sequence, and a true plot, in which one scene prepares for and leads into and causes the scene that comes after it.
I like to think of what happens to characters in good novels and stories as knots--things keep knotting up. And by the end of the story--readers see an “unknotting” of sorts. Not what they expect, not the easy answers you get on TV, not wash and wear philosophies, but a reproduction of believable emotional experiences.