Write. Then write. Then write some more. As an author, you will be expected to have a "voice," and the way you develop that is to practice. I bounced from modern fantasy, to action/adventure, to classic fantasy, to police procedural, to cozy fantasy before I was dragged kicking and screaming to steampunk. This is my home now, and I don't consider anything else. The point is, try everything. When you land on your home base, you'll know it, even if you never suspected it might be your preference in the beginning. Explore it all, and above all, have fun!