What I want to see:
Enclosed is my story, [Title], of approximately X words. [One to two sentences about who you are and how you are an under-represented minority, where applicable.] I have previously been published in [venues] and have been nominated for/won the [award] prize.
Thank you for considering my work.
What I don't want to see:
* A long personal history
* Descriptions of your unpublished novels
* A paragraph about how you were published in 95 junk publications
* Self-published credentials listed as legitimate credentials
* Spelling and grammar errors
* A cover letter addressed to the wrong publication
* A statement of who your favorite authors are or who most influenced your writing
* A summary of your story
* A description of what your story "means"
* The whole story embedded in the body of your email
* Huge irrelevant jpegs ("Look! A garden background!" "Look, here's me, on a rock!")
* Solicitations to promote the work you haven't actually completed yet
* Any statement of the type "This work is a good fit for your publication because...", "I feel this story is a good fit for your publication...", "This story fits with your mission because...", etc.
* A statement of how much you like/appreciate our mission and our work, while attaching a story which goes directly against it or has nothing to do with it at all
* A statement that you know your story probably isn't what we're looking for, but you decided to send it anyway
* A statement that you carefully read our guidelines, and your story complies with them, while attaching a story that goes completely against the guidelines
* Impersonation of someone else (another author, some random other person on the internet)
I'm probably preaching to the choir posting this here, but it needs to be said somewhere.