As a young writer, I read a lot of books about the craft. They all have a few common threads--success as a writer is mostly due to diligence, hard work, and perseverance--but I'd like to share one (though I'm far from an expert) about what makes a good story. It involves putting character above all else.
Motivation is paramount. Greater than what he likes or dislikes, greater than his appearance, greater than what he does for a living. I've found that the veteran writers who share their insights all agree--without believable character motivation, a story will flounder and fall short of greatness.
Easier said than done, I say.
So here are a few questions I've molded into my own checklist, which I reference whenever I'm in a funk on a first draft or editing a completed story.
First, what does he want? How far is he willing to go to get it? Or, What rules is he willing to break?
What is he afraid to lose? To what lengths will he go, and what will he sacrifice, to protect it?
What does he value? And, what might happen to cause him to throw aside that value?
What strengths and weaknesses will help/hurt him?
(Substitute "she" as needed.)
The answers to these, revealed in the prose, make the character seem more than a list of traits and closer to an actual human being that we might know from our own lives. Try to answer them from your favorite story or novel. I've found that the answers to the hard ones, the ones about breaking rules and discarding values, are the ones that reveal a great story.
So next time you're stuck in a rough draft and feel like asking, "What's this story about, anyway?" instead ask, "Who is this story about?" It might set you (and your main character) back on right paths.