Alright well, there are a few places that need some adjustment. The stroke widths for the body, mane, head and tail are all a bit inconsistent in places, you need to try and stick to one line width from the beginning to keep it all the same.
Lines such as the eyelashes absolutely need to end in a point (except in rare circumstances depending on the pony). From what I can see your eyes are fine, however some of the lashes seem to be cutting into them, which is easily fixed.
The other main thing is some lines are a bit bumpier than they should be. This is easily fixed by reducing the amount of nodes you use. Over time you learn that using less nodes in fact makes it easier. Aim to use as little as you can, and your bumps should disappear.
Looking at high quality vectors like the ones in the MLP Vector Club is a great way to see examples of how everything should look.
Also, if you arent quite sure what areas im talking about here, I can download the file and circle over them for you to see in another post.