Think Big! Consider that the word "Epic" is in the genre title!
Epic Fantasy in and of itself is a very big thing. An epic fantasy novel says to the reader: some very big things are going to happen here and you are going to see some amazing things.
With that in mind you should transpose this aspiration to your writing. What I mean is that you should aim real high. Shoot for the Stars! Pull out all the stops and make it BIG! It has got to be an epic and it has got have some great fantasy! Don't hold back. Give it everything you've got and when you are totally drained and out of ideas reach deep down and dig some more.
The characters in your work are going to face enormous obstacles and (hopefully) overcome tremendous adversity. Shouldn't you do the same?
There are plenty of great writers out there. They number in the tens of thousands and they all can write a great story with believable characters and interesting plot twists. They can keep the reader turning the pages and wanting more.
But not too many of them write with enormous multi-colored brush strokes that strike deep at the heart of being human is all about. Most of these writers climb interesting mole hills and lend their unique perspective on what the mole hill is like.
If you want to be a writer of epic fantasy you need to set your sights on the biggest scariest mountain you can find, set your pitons grab your rope and just go for it. Now that's what epic fantasy is all about!