you should make use of layers to make your vector cleaner, there are parts of it that don't quite match up that can be easily fixed by doing her tail a layer under her body for an instance and allowing it to bleed over the lines since the body covers it anyways.
Also you should try doing it in a higher resolution while first learning vectors it gives you more space to work with and actually makes it easier.
Also it appears you're running into the edges at a few points making some of the edges awkward always use a canvas much bigger than you'll need so you can move things around adjust and have extra space for manipulating the lines.
Coming from someone who literally did their first vector the other day (of Rainbow Dash) I wanna say that you've done a damn fine job! The online advice I can give you is continue to practice and keep it up! ^-^ Bro-Hoof /)