It can be hard enough to write a story based in the real world and keep the details straight. Writing in a fantasy world can be a pitfall unless you set certain rules right from the start. Once you decide what can and cannot be allowed, you have to stick by it, and not just change the rules later to enhance the plot.
I tend to treat my fantasy words as real places, which helps to keep me out of trouble by not getting too elaborate. But mostly, it's just developing a feel for the worlds you create, what will fly and what won't, that leads to consistency. If a writer doesn't get that sense for the world they have made, it will be damn tough to keep it in line.
Thank you for your kind appraisal. 🙂