Recently, I was asked what I do when I write a contemporary paranormal: "Don't you just make it all up?"
Well, you do have some latitude writing a paranormal. Of course, there is the world-building you have to do - your paranormal world should have rules and be consistent. It also helps if it overlays the world that exists, so the reader can place him or herself within the fictional dream. However, when writing any book, research is necessary.
When I wrote Sacred Guardian, I was hampered by the fact that it was based on events that were happening to me. I kept trying to write it as it happened, but real life can't be forced into a novel. My critique group found it too long, and worse yet, the heroine was way too boring. Ouch!
Once I gave up on trying to write it as I was living it, I knew I needed to bear down on a section of the experience, choose one angel, and tell his story. I was able to keep several scenes that actually happened to me in the book, but needed to do extensive research for the hero's life as a Lakota in South Dakota, both in the late 1960s, before he was killed, and current day Lakota life for the nephew he guides. I got several books on the Lakota language as well as tapes on how it sounds. I also got several books on Lakota life and scoured the internet. However, regardless of how much you research, there is always something you may not get quite right, so it is good to have an "expert" you can ask, which in my case was my aunt who lived near the area my hero was from and who read my book, chapter by chapter, asking her Lakota friends if it passed muster.
Another area where I used interviews of "experts" was for the death of my heroine's husband before the angel came to guide her. When he was in his twenties, my son's father was engaged to a woman who was hit by a car on Clement Street in San Francisco and killed right before his eyes. Enough time had passed so he could talk about this, but he told me that "it never leaves you." Losing a loved one who is killed before your eyes just does not go away. What I used from his account was the disbelief over what just happened, the small things that stand out in bold relief against something unimaginably painful and horrific. In the case of my heroine, I chose to have her attempt to get the exploded air bag from the car accident away from her husband's face "so he could breathe." She knew he was dead, but still found herself desperately pulling the air bag away from his face.
Researching the landscape of your book can include travel to the area or research online and in books. For Sacred Guardian I thought I had it easy. I set it in Berkeley, so all I had to do is walk outside, right? However, writing a book over time meant that businesses that were thriving while I was writing it disappeared in the economic crash when I sold the book, so I had to go back and make up names of stores my heroine passed on Shattuck Avenue to replace the businesses that were there when I started the book.
Research is really a fact of life for a writer, whether writing fiction or non-fiction. It is also a delight for people who love to dig deep into a character. Creating that character's life, where they lived and what shaped him or her, is part of the joy of writing fiction.