Ideas for a fantasy novel?

I love all of the things you've listed. I read books about fallen angels, vampires, werewolves, faeries, but I have never heard of succubi. Anyways, I think it really depends on who you want your characters to be. As for writing it, I would come up with ideas that would lead to the end. That's how I'm doing my story. My story is about a wizard girl and a vampire guy. My story website: www.magicandblood.weebly.com. Hope I helped. Enjoy.