I believe in the art of rejectomancy, I really do. In fact, I'm a master. Show me a rejection letter and I'll tell you exactly what it means. It's an amazing power I have.
You can have it, too.
Rejectomancy is the art of reading between the lines when you get a rejection letter. It consists of parsing each word, perhaps even every syllable, for deep clues; checking response times, and maybe even doing a bit of etymological digging on exactly what the words "commend" and "unfortunately" really mean.
Here's the truth from someone who's assembled over 100 rejections just last year and has sent ten times that many over the years as an editor. Rejections mean exactly what they say. No more. No less.
Think about it: why would any editor try to speak to you in code? They either want your work or they don't want it. I'm not saying that you can't sometimes read between the lines; I'm saying you don't need to. In virtually every case, the rejection says it all at face value.
Here's three good signs, but you won't have to decode anything to find them:
1) An editor asks specifically to see more of your work.
2) An editor mentions one or more of your pieces by name and specifically commends your writing.
3) An editor mentions that your work was shortlisted.
Other than that, you can't read anything into a rejection letter that really means anything. In most cases, a writer's work is rejected because it doesn't fit with what the publication is looking to publish. Often, this is a case of quality, but it is also sometimes a question of fit.
If you're like me, you probably sometimes get "nice" rejection letters asking you to submit again and saying your piece just didn't fit this time. That means exactly what it says. Editors like to "match" works when they publish them for whatever reason and they do so in ways you can't possibly foresee. If a specific editor has to choose between two equally good pieces, but one fits with the feeling of the issue they're building, the one that fits gets in. This is a purely subjective thing and it's not the same as having a stated theme.
What can you do to improve your odds? The answer is: not much. But here's a few things to try.
1) Study the publications you submit to. This is easy nowadays because almost everything is online. Don't submit to places that you can't see your own work slipping into comfortably.
2) If a journal. pub, or site form-rejects your work more than six times, stop submitting for a while. Whatever you're doing right now isn't working for them. If your style changes, maybe you can try again.
3) Try to submit as early as possible in a given submission window. For obvious reasons.
4) Send the maximum number of poems you are allowed to send. Try to send a range of themes.
5) Send poems under 20 lines. Shorter poems are almost always easier to edit and "fit" in for most places, even when they're online.
6) Submit only fully edited, finely polished work.
I've got a lot ore to say about rejection and submissions in the future so stay tuned. Meanwhile, good luck with your own work and hope you drown in acceptances!