I am hopeful that you understand that Mulan reference, and if not, get of my website and go watch Mulan. Alright, now for the actual advice part of this post. One things I needed to learn when I first started writing was when to detail and when to not detail. When I was a little writer (littler than I am now, actually) I didn't detail, and then I detail too much. Right now I know that when a scene has a lot of emotion, movement, or beauty in it, you need to add as much detail as possible.
When a scene is a little slow and just for plot, you really just need to plow through and have the reader not get bored with what you're writing. All of this is really confusing, and if I don't explain it well enough, Google it. Having different people give different opinions on one subject is a great way to come up with the mist effective way of doing anything.
A lot of people find it hard to write a really good story in a small amount of words. I don't have that problem. I once wrote a story that had six sentences and make people cry. Let me tell you something, it's all about the amount of detail you put into the story. With a regular sized novel, you can span out the detail within chapters to keep the readers, you know, reading; but you can't do that with short stories. The readers need the information and detail near the beginning so they kind of understand what has happened in a short bit of time.
If there's one thing I should say about writing short stories is, just let the story write itself. Don't plain anything, don't outline, just let it flow. It's how a good story is supposed to be written. Don't think, just write, you can get the rough edges out later.
this is where i ramble; have fun