All editors expect that writers will know what audience their piece is for and write accordingly. A high school newspaper editor expects that her writers will write for their high school classmates, submitting articles of interest to and about the student body. An editor at a magazine or publishing house expects that submissions or queries made to her will be suited to the magazine's readers or meet the needs of the audience the publishing house seeks to attract.
Editors also expect that writers will know the house style for their magazine or news publication and submit material written appropriately. An editor for a newspaper or news magazine will typically expect writers to refer to the Associated Press Stylebook and write accordingly, while an editor for a scholarly journal will expect writers to use Modern Language Association style. Editors of nonfiction books usually expect writers to follow the Chicago Manual of Style. Editors for trade journals or specialized topic areas may also have their own style guides they expect writers to follow.
While copyeditors catch typographical errors, grammar and other mistakes, they expect writers to proofread their work before submitting it. Editors expect that writers will correct basic spelling errors and punctuation mistakes and that submitted work will be clearly written and organized. Writers should not submit sloppy work, assuming the editor will fix it for them. Writers stand less of a chance of having their work be accepted if it's riddled with errors, even if the content is good.
Whether the editor generates the story idea or the writer proposes it, the editor still expects the writer to complete an article, story or book that has something to say. Editors anticipate that writers will provide an informative and interesting take on the subject, whether reporting the news of last night's ball game or submitting a biography. Writers should have an engaging perspective or provide new information in an engaging manner.
Writers who've been given specific assignments will typically be provided with article lengths and submission deadlines. Editors expect both to be followed...and have little tolerance for writers who fail in either case. When given a word limit of 500, for instance, it will be frowned on to submit an article that's 1,000 words; it may not even be accepted. As for deadlines, they're critical in the publishing field, so it's best to plan to finish articles at least a few days before they're due rather than risk turning in something late.