As authors make sure you remove as many spelling and grammar errors as possible before you submit your work of art. Do use the spelling and grammar tools of your word-processing software BUT don't rely on them exclusively. A lot of spelling and grammar issues can slip by. In particular, a misspelled word can be auto-corrected to become another word. Try reading your work out loud to separate yourself from your work and catch these gotchas. As an editor, I don't have preconceptions of what a piece says so it's easier for me to spot problems.
Be careful with word choice. I know authors who love their thesaurus, but not all words are created equal. Consider what a word really means. And is it consistent with your world and character? This is also something editors look at.
Probably the most common thing we edit for is length. IMHO, rarely does a short story need to be 5,000 words or more. I know Electric Spec accepts longer stories but those extra words are almost always padding--and padding that obscures the true beauty of a story. One of our editors (his name rhymes with Dave) is a master at revealing a story jewel hidden underneath the fluff. We call him The Slasher and all try to emulate him.
Related to this is where the story opens. Often a story opens with a lot of setup or backstory. Often this isn't needed.
An editing trick I've discovered over the years is line spacing. White space on the page or screen is your friend because it imparts drama. It lets the reader focus on a particular sentence. Go ahead, try it. When something important happens, put that sentence in its own paragraph. I often recommend the climax--especially the emotional climax--of a story get its own paragraph.
Didn't you focus on the above line? Of course, the opposite holds as well. Readers focus less on stuff in a long paragraph.
A similar idea for dialogue is to break up dialogue with beats, small physical actions or expressions. Here's an example:
"I love you." She swallowed. "And I've never said that to anyone before." versus
"I love you. And I've never said that to anyone before."
Isn't the first version more dramatic? Breaking up the dialogue makes the reader focus more on the individual lines.
Authors selected for the awesome August issue should be in the process of sending back their contracts. Once we receive the contract, the Editor begins editing. If our proposed changes are minor, we'll post the story in a preview and ask the author to okay it on the webpage. If more significant changes may be necessary we generally go back and forth with the author giving suggestions, etc.
Be sure to checkout the new issue August 31!