The first thing I want to impart on you is about the very nature of "fantasy". It implies an act of creative imagination. That is great for you as a writer. You are writing a story and building a world. And it is your world. Absolutely anything applies! Write anything you want to write. Don't be boxed in by traditional rules of fantasy. You are in control of everything and nobody can tell you otherwise. Let loose and just see where you imagination takes you.
And this doesn't just apply to the characters, world and story. This also applies to the rules of writing. Want to write your whole novel in a new language that only one-eyed centaurs speak? Go with it and see where it takes you. Want your story to jump around in time -spanning ten thousand years? Cool! How about writing it in epic poem style or from varying points of view? This is your world. Write it any way you want to. Don't be afraid to explore the mechanics of writing in new ways. If you have this nagging feeling that you should be writing a certain way then why aren't you?
Here are some tips and ideas on what you can tinker with in your novel to make it more creative and different
Time - This is one of my favorite things to tinker with. Time doesn't have to plod along at the usual pace. And If you have been writing for a while you have become a bit sensitive to time, nd you probably already tinker with it. Does a two minute sword fight take two minutes to read? Nope. The basic rules of time need not apply to your writing. Want to write your whole novel in the one minute life span of some type of fantasy creature? I think it would be fun and challenging.
Perspective - Is your main character human? That's perfectly fine but wouldn't it be a challenge and a lot of fun to use some kind of other creature as your narrator? How would a strange fantasy creature think? An easy way of looking at this would be from the perspective of a dragon that lives for thousands of years. Wouldn't that dragon have a whole different outlook on the world - based on an accumulated wisdom.
Creation of systems and beings - This is where you can have a lot of fun yet still impart something special to your readers. Aren't there already enough ogres, elves, and dwarves tromping around the pages of fantasy novels? Couldn't you come up with something new? Draw some sketches and write down outlandish ideas. How about a whale sized creature that floats through the air eating microscopic bacteria? Or a race or elf-like creatures that fire electric eels from their bows? As far as systems go wouldn't it be different to have your adventurer stay in one place and have all the adventures come to him? Rather than tromping around the world maybe the world would come to his front door. How about a world where every single living creature falls asleep for the duration of the full moon? It would be fun to find out what happens when they all wake up.
Some cautions for your new imaginative writing
Just because you are writing something new and creative doesn't mean you shouldn't have any discipline. You are still writing for people. And people have expectations. That means there has to be a certain logic and sense in your world. You have to lay out rules in a way that the reader will understand and accept as natural.
So don't find yourself falling into the trap of just coming up with something to solve a situation or crisis. One of the worse things you can do is just all of a sudden grant your main character the ability to cast a spell that solves a problem. Don't bend your rules to make your story work. Layout your rules then work within them.
With a little bit of imagination you can come up with a world and a story that is totally different, yet totally rewarding for your readers. Let yourself loose, try different things, and see where they lead. You are the creator of a totally new world and just about anything goes. Just make sure you temper it with some discipline so it makes sense.