My major influences are horror and sci fi. But while learning to write, I spent much time exploring classic literature. I have read works by all three Bronti sisters, Herman Melville, DH Lawrence, Charles Dickens, Bram Stoker, and Mary Shelley.
I love getting frightened, and intrigued. Stephen King was the first writer I absorbed in near totality, and then it was Carlos Castaneda. From there I went to Anne Rice, and then Robert Silverberg. Currently I'm reading everything by Jon Krakauer.
When I think of what makes a good horror book, I think of intrigue. When we want so much to believe in the supernatural, or in legends, and then find ourselves in a mysterious situation, it makes the blood run faster, and the adrenalin flow. A good writer can bring us there.