What makes a good story? Good question.
Well, a good plot is essential, as is believable dialogue but, the only way of knowing if your writing is any good is to get other people to read it. Creative criticism, before submitting your masterpiece for a competition, is a good way of improving, or tweaking it before you send it off to fend for itself among hundreds of others.
Saying, 'That'll do", will never win competitions so don't rush things. Read it and re-read it. Ask yourself questions.
Can any over complicated, wordy, sentences be rewritten to make them more streamlined, or flow better for the reader?
Am I using too many words to describe something?
Does my dialogue make sense?
Are there any spelling mistakes, errors or plot holes?
Get the above wrong and you risk making it hard work for the reader to stay focussed. No one likes re-reading complicated sentences or be forced to frown, bemused, at weak dialogue.
Its the same for competition judges. Force them to stop reading and they'll stop reading. Full stop.
Take heed so your story doesn't end up like the boat in this picture. You can form your own interpretation, but you get the drift.