And more advice from someone more experienced than I:

Slushmaster (at Realms of Fantasy): „A Reason to Keep Submitting“
The point is, for all you fledgling writers out there, you have to keep submitting. There is a good chance that if you refine your writing skills to a publishable level there will always be that one editor who doesn't get/connect with your stuff, and your stories will be rejected no matter how brilliant they are, and no matter where else you've been published. But, and this is the most important part, one rejection from a market tells you absolutely nothing. You have to keep submitting, over and again. Some of these markets will keep sending you standard rejection letters. It doesn't mean you should stop submitting to these places, but if you've received a dozen standard rejections in a row, now you can safely assume this will be a tough market to crack. Meanwhile, if by your second rejection from a good market the editor is telling you "try us again," well, your chances of cracking this market are obviously better. But you'd never learn this by giving up after one rejection.


And in the comments to the above, someone helpfully linked to the following:
James Van Pelt, from "Perseverance, Publishing and the Urge to Write"
I have never sold a story to the first market that saw it. However, last year I sold a story that had been bounced thirty-one times previously.