Get into your characters’ heads as quickly as you can. Can you sum up their main characteristic in one or two words? Can you sum up your story in a line or two? Are your characters different so you can tell them apart? Do their voices sound different so nobody is confused as to who speaks?
Moments of weakness in a character can be used to strengthen their portrayal. We all have moments like this - fictional characters should reflect that. It is then what real and fictional people do after having such moments that can add or make a story.
Proverbs are a good source of basic plot ideas which can be expanded out.
Look at what your characters have to gain or lose. Is that motivation strong enough for the plot you’ve got in mind?
Raise your characters’ problems, ambitions, ensure there is enough tension in your story. You do want to make a drama out of a crisis! (Without overdoing it of course!)
Consider politics! Whatever your fictional world, it will come into play. How does it affect the ruling classes? The peasants? How did the politics come about? Is there gender equality? Freedom of belief and/or speech? Are broadcasters, journalists or their equivalent free to report as they like or are they subject to controls and who operates those?
Get the balance right between dialogue and narrative. Nobody talks all the time! Keep the narrative fast moving.
Give your characters hell! They are not in your story to have an easy time of it else there’s no story. Flaws and virtues must be realistic. A character struggling with a weakness and every so often succumbing to it and then battling back is always interesting to write and read about.