Preparing fiction for the wild -- first, FINISH the things! (Seems like a funny thing to say, but I know a lot of aspiring writers who never have actually finished a story or a novel.)
Once they're done, have someone ELSE read them. Join a writing workshop (the Online Writers Workshop is FANTASTIC for science fiction, fantasy and horror. For erotica, I recommend the Erotica Reader and Writers Association -- they have a Storytime mailing list where you can post your works for critiques.) Listen to what they have to say -- you are NOT the person to find the little nits in your story. Not at first, anyway. (I've gone back weeks or months after, reread something and went "Yipe! How did THAT get past me?" One of these was already in print, so it got past me AND my editor!)
Then, once you've listened to your beta readers and done your own revisions, and once you're just about to reach the point of pitching the story out the window... THAT is when you send it in. ;-)
Be patient. Publishing is SLOW. It took almost a year and a half for my first sale to finally see the light of day.
Publishing is also subjective. Do not take rejection personally. If, however, you have several rejections on the same story or novel, that might be the time to take a step back and regroup. Have you gotten any nibbles on your query at all? Might be time to rework the query letter! Have you gotten partial requests or full requests, but no takers? Take another look at the novel or the story. It might need more work. (Query letters and partials are pretty much only for novels. If you're submitting a short story, you submit the WHOLE thing.)
Hope that helps! Please feel free to ask me anything else!
If you're going to try the foreign market, then you really do want to talk to someone in the know (if not a publisher, than a publishing lawyer). There are legal issues that I'm not even going to PRETEND to understand.