I just finished reading for a ghost story anthology. As usual, the overwhelming reason stories were rejected was they didn't comply with our writers guidelines. I'm never really sure if the writers sending these stories in don't bother to read the guidelines or simply do not care. But, a story where you need a haunted hotel shouldn't be getting stuff with people wandering around in outer space, or struggling with haunted cars--but we did. And this is consistent with other books I've done. If you take away those stories that do not meet the writers guidelines we put out, almost every one that did comply was accepted.
Now, that's not an automatic template to success. Some writers guidelines are so vague you can't really tell what a project actually wants. But, if they say it needs to take place at a haunted hotel--put the story in a haunted hotel. If a story is supposed to take place during the 1800s, don't be all that shocked that your World War II story is being rejected. Seriously. It is simply astonishing how often this happens.