My editors make my work better by ensuring the work is right for the audience, that it has a cohesive and logical structure, and that my references are up to standards. They also catch any spelling, grammar, or punctuation mistakes that weren't caught by either myself or Microsoft Word.
A decade ago, I wrote for newspapers, and I eventually worked as a writer and editor for one of those papers, so I've had some firsthand experience of what editors do. I know that I seriously appreciated work that had thought and effort put into it. Even the basics like spell checking and making sure punctuation is used correctly make the editor's job significantly easier. When writers take the time to get the basics right, it gives the editor more confidence in the writers' sources and facts. These things still have to be checked, of course, but seeing 500 words of misspelled, ungrammatical text inspires many levels of dread on the part of the editor.
I have been lucky in that my editors are extremely professional, and when they assign me work, they give me enough information to lay out a cohesive structure and fill in what's missing. And on those rare occasions when a topic is obscure enough that I can't do much with it, they've gone to bat for me and come up with a better topic or assigned something else altogether.
I suppose the point of all this is, if you have an editor, do your part to send in clean copy that's well-structured, and use solid references, including links. Not only will you make his or her workday better, you're more likely to get good assignments, because you're reliable and make him or her look good.
Of course, if you don't have an editor, you have to act as your own. Ask yourself, "If someone turned this in to me to publish, would I be happy with it? Does it make sense? Is it mechanically correct?" Some clients are pickier than others, but if you act as your own editor and your own "picky client," you'll raise the standards of your work and maximize chances of getting the best assignments in the future.
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