Over the past year, I have discovered a few things about submitting stories and the guidelines they post on their website and, sometimes, in their rejections. Here's a few tell-tale signs to keep in mind.
1. Beware the "Buy our magainze to find out what we like." You should be able to tell from one reading what they like. Don't think because they have a pirate issue they want to see pirate stories. Normally, this means they seen a lot they like, but are tired of them.
2. So, what are we supposed to gleen from what they like? Well, ask yourself questions about the structure of the story. Namely, what is the character doing? Are they growing? Is this something where they are coming to some sort of realization? And so forth. The more you learn about the structures of selling stories, the more you can learn about what they want to see in a story.
3. If a market says "dark fantasy," unless you know what that means, submit anything "Dark" and anything "Fantasy." Some publishers may have different areas for Fantasy and Sci-Fi. Others may have a lighter publication they can refer you to if they like it enough. Or, they can like it enough to buy it.
4. Submit Everywhere. Yes, I know, it sounds strange, but trust me, submit everywhere. Sometimes, you are the worst judge of your own work. You may think you have something for Market A when Market B is interested.