"Your story seems kind of random and disconnected. I couldn't figure out what was going on."
If this sounds familiar, congratulation! You're a writer, Harry. Welcome to another episode of:
Ellie Raine's School of Wordcraft and Scribery!
"Hey Ellie, what's the one thing you most love about good stories?" Thanks for asking, Ellie's internal dialogue! That's an easy answer: Synergy.
The one constant thing with every book/comic/videogame/movie I've ever loved was how synergystic it was.
"Well, what is synergy?"
According to Dictionary.com, Synergy is defined as "the interaction of elements that when combined produce a total effect that is greater than the sum of the individual elements." Basically, in terms of story, it's the overall balance of the plot's elements that work well together. You know the Final Fantasy game series? Why is it each game is so different but the worlds introduced are just so damn real? Synergy. The characters look and act like they belong in that new world, the plots are extremely thematic within their own designated parameters, the magic system is (usually) reasonably limited and doesn't break it's own rules...
*cough* shut up, Cloud, I know you could have just used a Phoenix Down on Aeirth and a Soft on Red XIII's Da *cough*...
... But the point is, if those individual elements weren't balanced, the world and story would fall apart.
Imagine a fine tapestry. Each individual thread is, well, just a lone thread by itself. It might be the silkiest, strongest thread you've every pinched between your unworthy fingertips, but it will never be anything other than a single thread. And there are thousands of threads that are special in their own way. Once they're woven together, they create the whole tapestry. Each thread is integral to keeping the work in one piece.
Now imagine if one of those threads was weaker than the others--A hole is torn in the tapestry. Two threads? The hole rips deeper. Three? Four? Five?--the whole thing unravels and shreds to pieces. Those tiny threads are your story's elements. Pay attention to all of them.
One or two weak threads can be overlooked most of the time, but the more attention you give each one, the silkier your tapestry will be.