A simple way to think about plot is as the events seen in the light of their endings. Endings are important, and one of the most difficult parts of story-telling. A good ending should be both surprising and inevitable.
Write a cracking-good ending (a paragraph or two). Then work backwards and develop the sequence of events (the plot) that leads up to this ending. Note that this may feel very artificial for writers who like to “discover” their ending in the course of writing. But it’s an exercise to help us be aware of the sequence of causes that create good endings. It’s also a great technique when you’re editing a story to do a “backwards pass” and check that you have properly motivated the ending. A “backwards pass” is exactly this process of working backwards from the ending.