THINGS I DON'T WANT TO SEE IN ANY FAIRY TALE (OR OTHER STORY)

1. Weak characters as they won't hold my interest and I think are the biggest factor on those, thankfully, rare occasions I give up on a story.
   
2. Magic being used to solve each and every problem.  It is far more interesting from a storytelling viewpoint that magic causes its own problems and/or weakens someone every time they use it so it forces magical beings to find other ways of resolving issues.  It also means those less powerful magical beings have a chance of (a) survival (!) and (b) of getting involved with the issues of the day on their fictional world and playing a good role in this.
   
3. Excessive violence.  Any violence, regardless of genre, has to be appropriate for the story (and so the age range of its targeted readers).  It is possible to overdo it.  Is what you've written necessary?  (If it is, you'll easily be able to justify it).  Personally I am put off by excessive violence.  I like a good crime story but don't need the gore and while that is personal taste, I'm far from the only one having that view.  Write to the readers you want to attract.
   
4. Characters being all evil or goody-goodies.  Nobody is like that in life.  They shouldn't be in fiction either.  (Characters who are either all one thing or another with no shades of grey are just caricatures of a character).
   
5. Coincidences.  Yes they happen in life but in fiction it is like writing "it just happened".  Your readers won't buy that.  You can and should set things up so that when "coincidences" happen in your stories, your reader will be able to trace back steps that could genuinely lead to that coincidence occurring.  It must not come out of the blue.