The efforts that go into weaving the details that would make a(n) (hopefully) airtight plot are done with care.
Things within the story have to make sense. This doesn't necessarily have to mean that it has to make sense conventionally, but it has to logically follow the set up of the story. There has to be a beginning, a middle, and an end. There must be actions or motives that cause a reaction, therefore propelling the story.
There must be reasons that create the whys and hows of the story. This is why outlining comes in handy. (I swear, I'll get to outlining...someday.) A general outline of the plot can be fleshed out, and then the more details surface, they can be added to the outline as needed.
Do any of you have any plot pointers you wanna share?