Synopsis: Twilight starts coaching Rainbow Dash, and that turns romantic somehow.
Critiques: Prereader 12 is right, this story doesn't really have a sense of flair. And by that, I think he was trying to say that this is pretty cliche and doesn't really add anything new to the table that hasn't already been done in various other Twilight / Rainbow Dash stories. But, I'm not trying to put my less-polite words into PR-12's mouth, so I'll avoid conjecture and stick to my review of this story.
Stylistically, you've got a lot of stilted sentences that don't flow into one another in a very natural-sounding manner. For example,
>It was just a little more. Just a little more and she would break the barrier. She had tried every day for the last month to perform this trick. But this time was the time she would succeed, she told herself.
I'd personally go with:
>Dash pushed harder, egging herself on. Just a little more... After trying every day for the past month, today was the day she was finally going to succeed.
That's two-and-a-half sentences (direct thoughts and dialogue don't have to be complete sentences), down from four, and it portrays the same idea of Dash pushing herself harder to try a trick after a month's worth of practice.
Also, be very wary of starting sentences with the same "pronoun verbed" structure, especially in the same paragraph and especially when they're back-to-back sentences.
Moving on, you should also be wary of putting dialogue back-to-back without any character actions. Actions can say more about an interaction than the dialogue. For example,
"Did you pick up that gift for your wife?"
"Yeah, she's going to love it."
Marcus turned the ignition, and the car purred to life. "Did you pick up that gift for your wife?"
"Yeah." Steven pulled the nine-millimeter out of his jacket and cocked it. "She's going to love it."
So yes. Fun with gangsters aside, you're missing a huge opportunity to augment dialogue with emotions every time you don't pair an action with it. Now, granted, don't oversaturate dialogue with actions, and work on writing emotions and such in a rich, varied style, but as it is, right now, you're too far on the "not enough" side of the scale.
Moving on, and finally my biggest concern for this story: I'm not exactly sure where their romance is coming from. Like, it happens, on page 4 or 5, where Dash has a Freudian slip or something, but up to that point, there was nothing hinting at romantic interest. Not a hint, nothing beyond "friendship." In a story that's limited to following one of the main characters (especially in emotions and perception), this is unacceptable.
In closing, I'm really not sure what to tell you about EQD. You've got work cut out for you to polish this up into a "well-written but cliche" story of Twilight Sparkle / Rainbow Dash's romance, but even after all these fics, you're going to have to think of some way to try and set yourself apart from the pack. But that's more "for getting onto EQD," which, believe it or not, has more requirements than the story being good—it's got to be more or less original, too. And shipping tends to get hit the hardest, as there's only like thirty different combinations of the main six.