The first story I sold to a professional market – that is to say one that paid money, not contributors' copies – was to Pocket Books. I won a slot in the annual Star Trek: Strange New Worlds anthology with a "Voyager" story.
The Strange New Worlds writing competition (SNW) was for new writers – those with fewer than three professional sales. Every year of SNW's ten-year run hopeful writers sent in two thousand to three thousand submissions, trying to earn a slot in the twenty-story anthology. Though the competition was fierce, with few exceptions members of the Trek online writing community were open and mutually supportive. Soon after the winners were announced, I began receiving e-mails from writers who had not won asking me how I did it. A few were looking for a secret password or the name of the person who could get them into the anthology so the biased judges couldn't keep them out, but most had questions about the craft of storytelling. Several asked me to look at their stories and tell them what they might do to improve their chances.
Being a big believer in paying things forward, I didn't think twice about offering to help. Which is how I quickly learned something about writers most editors have always known.
The rules governing content for SNW stories were pretty basic. 1) You can't kill any of the regulars; 2) You can't introduce a character who's a lot like you who becomes the savior/love interest/best friend of everyone aboard the Enterprise(s)/Voyager/DS9 [this is known in the industry as a Mary Sue story]; 3) No love affairs not in the TV show [we're looking at you, Kirk/Spock fanfickers]; 4) No suddenly discovering a major character has secret children, especially if he/she didn't know about them; 5) no copyright violations, as in no Star Wars/Stargate/Powerpuff Girls crossovers; and 6) No changing events that have already happened in the series.
Because I'd won with a "Voyager" story, most of the people who asked for help had also written for "Voyager." If you are not a Star Trek: Voyager fan, you can be excused for not knowing a character named Kes was written out in season four and a new character called Seven of Nine introduced to replace her. This transition did not sit well with the Kes-iphiles in the fanbase. Fully a dozen Kes fan writers who could not understand why their stories hadn't made it had submitted variations on Seven of Nine getting killed off and Kes coming back. There were as many Mary Sues, spanning all the shows; a handful of crossovers with other intellectual properties; one that was based on a popular song of the sixties (as in people spoke the lyrics as dialog); and one in which it is revealed that a major female character had given birth to a child fathered by Lore and didn't remember the event or the child. Lore is an android. (No, not the phone.)
I wish these stories had been terribly written; that way I could excuse the writers for not understanding the rules they were breaking. But the fact is most of them were well written and one or two were excellent. The writers knew exactly what they were doing but – and here's the thing any editor could have told me going in – they felt that their story was so good it didn't have to follow the rules.
Every market has rules. A story that's right for Esquire will not be right for New Yorker. Analog does not publish horror and Ellery Queen does not publish romance. If you as a writer are determined to have your work published by a particular market, you need to study that market. This goes beyond the basic first step of knowing and following the guidelines of your target market. Read the stories they've published over the years until you can recognize an Atlantic story or an Asimov's story when you see one.
Of course a writer does not usually target a specific publication before writing a story. The traditional sequence is for the writer to write the story that's in her, then look for a suitable market. Standard operating procedure is for her to send it to the highest paying market first, then – if it gets rejected – to the second-highest, then the third, and so on until it sells (or she gives up). There's a strong case to be made for this method – it became the standard for a reason.
But an equally strong case can be made for recognizing what market would be most interested in your story and sending it there first. If you don't know, you should research until you do. This will not only make the submission process easier and more pleasant for you (because let's face it, reading a bunch of well-written short stories can't really be called a hardship), it will show respect for the editors who may – if you send them a story that's right for them – buy one of your stories. (And, no, editors are not being narrow minded when they stick to their preferences. If you want black appliances in your kitchen and the store delivers avocado green, sending them back is not being narrow minded – it's knowing what you want.)
Because you can't know what an editor needs on a given day, there's a chance the story that would normally be a perfect fit won't be right this time. So have a list of markets ready; if the story comes back from your first choice, mail it to your second.
The bottom line is: If you want to sell your work to professional markets – and there are a lot of paying markets out there – learn the rules of each market and then follow them. That's being a professional writer.