Aside from getting the conventions (grammar, punctuation) right, you want to make sure:
1) your novel has a sustained conflict through the book;
2) your main character(s) grow/change during the book;
3) your characters have goals and motivations;
4) you show rather than tell ("She balled her hands into fist and glared at him" not "shs was really angry at him."
5) You use active voice and strong verbs, not passive voice or weak verbs supported by adjectives. ("She hurled the cup at him," not "he was hit by the cup which she angrily threw." or "Clouds scuttled across the dark sky and rain beat at the windows" not "It was a dark and stormy night.")
What I hate: Characters who act in unrealistic ways; characters who are too unbelievably perfect (make them human); inconsistent plots.
This is pretty standard writing advice. If it's new to you, you should buy or get a book on writing out of your library. The For Dummies series has How to Write a Romance Novel and a few other writing titles. They should be easy for you to follow. While the Romance Novel title might not completely apply, many of the ideas could be generalized to Fantasy.
Also, you need objective critiques. There are on-line critique groups, or you can recruit friends and family. But, you really need someone who is willing to tell you what doesn't work, not someone who is going to think your book is great, regardless of whether it is or not. A teacher might help you there.
Remember, a first draft is a first draft for a reason. So, even if, as you learn more about writing (and we're all still learning) you see flaws in what you've written so far, you can fix and change things.
Good luck