- You can invent whole new worlds or use recognized fantasy backgrounds (e.g. a fairytale background usually does not need explaining).
- You can invent whole new monsters or use recognized ones (ogres, wicked witches and so on).
- Talking animals/creatures is not a "sin" in fantasy. I like well written anthromorphism (hate "cutesy" - as in all character portrayal, the dialogue you give your characters must "suit" and nobody speaks "cutesy". I always loved Animal Magic when I was a kid and never felt Johnny Morris's "words" that he gave creatures to "speak" on this show were out of place or not right for that creature).
- You have to limit magic (if not, you have no story because everyone can do magic and they cancel each other out. Restrictions include some people can't do magic or only use basic spells while others are more powerful. There has to be a clash element and resentment at others being able to do more magic is a good one to use. Magic also has to have a price for its use. If the more powerful can just dominate because of their skills here, again there is no story but if everyone has to be careful in how they use magic because it drains them, again you have clashes and tension points here, all good for your tale).
And as for some of the frustrations...
I'm Allison Symes and write fairytales with bite, especially novels and short stories.