On the subject of avoiding stereotypes...
I suggest becoming knowledgable with
common tropes. I'm also a sucker for historical (cultural, religious, literature, etc) references - they can be used to subtly foreshadow. So long as it's a classic story (heroes v. villains), consider reading up on the original classics - Greek, German, Celtic, etc plays and epics that established the genre. Who knows, maybe you'll pull some historical references from there.
And just for kicks,
a periodic table of storytelling, to get the brain juices flowing.