Foreshadowing is when the opening scene of a story is a kind of nutshell prophecy for the whole story.
The Beginning
* In a Horror, this is when the originating Bad Thing happens.
* In a Mystery or Crime story, it's when the first victim is slain, and/or object (McGuffin) goes missing.
* In a Sci-fi, this is where the ruling Theory is presented.
* In a Gothic, this is where the main character meets the monster he is about to become.
* In Erotica & Romances this is where the main character meets their soon-to-be lover for a fleeting but memorable moment.
This also reveals the Premise, or ruling argument that the story is trying to illustrate; what the story is trying to Prove.
• The results of Revenge
• The path of Ambition
• The reality of Love
• The pain of being Different
The Middle
The meat of the story should fulfill that prophecy using twists, turns, and surprises that compel the reader to Keep Reading to discover 'what's really going on?' Never forget: The readers DON'T want to see what's coming. They want to figure it out THEMSELVES.
However, if you intend to use (what looks like) chance and coincidence to move your plot you're going to need careful preparation. Using deus ex machina (situations, objects, and helpers that were just suddenly THERE without explanation,) is unacceptable. The author should NEVER pull a rabbit out of their hat simply to rescue their hero.
The trick is to put the plot element into your story EARLY without making the reader aware of its importance. Never telegraph your punches. Every choice made MUST seem logical for that character.
The Conclusion
The last part is what that prophecy brought about--what happened BECAUSE of the events in the story.
* Were the guilty punished?
* Was the lost object or person found? Plus who did it and why?
* Did the lover gain the attention of their beloved?
* Was the scientific theory convincing? (Or horrifying enough?)
* Did the monster reconcile with their nature?
Always complete each circle you began. Solve EVERY problem presented, no matter how small. Any unsolved problems become Plot Holes your readers WILL notice and call you on. "Hey, whatever happened with...?"
The easiest way to do this is by keeping your Main cast SMALL.
* Hero
* Ally (buddy or lover)
* Villain
Side characters are those who occupy places in the story: the waitress, parents, coworkers, the beat cops..., but don't actually change anything. Main characters are the characters whose actions actually affect the plot.
The more Main characters you have, the more problems you add--which means the more story you have to write to solve those problems.
Enjoy!
DISCLAIMER: As with all advice, take what you can use and throw out the rest. As a multi-published author, I have been taught some fairly rigid rules on what is publishable and what is not. If my rather straight-laced (and occasionally snotty,) advice does not suit your creative style, by all means, IGNORE IT.