For example, let's say you write a story where the protag is fairly interesting, the plot is sustainable (i.e. not jaw-dropping), but the world is awesome--something nobody's done before. Well, then you better show off that world right away in the best possible light. Get the editor so enamored of your world that he or she may be willing to overlook minor failings in your plotting
Another example. Let's say you've got a great plot concept. Something you think will really stand out. You don't have to show your whole hand right away, but you've got to clue in the editor that it's coming. If you can, do it in the first sentence, or at least the first page. An example from my own writing is when a member of my critique group pointed out two sentences that I originally placed four paragraphs into a story: "At first, Mary thought they’d been burglarized. But there had been no sign of forced entry, and the only things that had been taken were Donny’s memories." Why not move that to the very beginning of your story? asked my critique partner. I did because I knew it would "sell" the story better than my original opening.
So, before doing that final draft of your story, figure out the strongest aspect of the story and then decide if you've done enough to sell it. If you haven't, a gem might just slip through the editor's hands.