When you submit your manuscript for copy editing make it is the best piece you can write. Why go to all that work if it’s going to be ‘fixed’ anyway?
Each writer has, or should cultivate, his or her own ‘feel’ or style. The more complete the manuscript is that you pass on for copy editing the more likely it will retain your style rather than taking on that of the editor.
Make sure the vocabulary and sentence structure reflect your style. If you target the educated reader use words that acknowledge that level of understanding. If you write for the less educated modify the set of words you use accordingly. Some writers are known for the complexity of the sentence structure they use. Others prefer to set their ideas with simple sentences. A mix probably makes the piece more appealing to the general reader. Longer sentences often facilitate the feeling of easy flow within a piece. Short sentences provide a staccato, point by point, feel. Whichever you want to have characterize your style, make sure the manuscript you turn over for copy editing reflects it.
Always perform the spell check function so the copy editing doesn’t have to involve such menial aspects of the piece. The better spell checkers will locate inappropriate homonyms (sound alike, spelled differently – there/their). In terms of the ‘sentence fragment’ warning, remember that all incomplete sentences need not be fixed. In dialog, for example, some speakers may typically talk in phrases and incomplete sentences. That adds realism if it is true to the character. Even in the non-dialog areas of a piece fragments may (judicially) be allowed if they are used for emphasis (‘He was sad. Somewhat melancholy. Depressed, even.’). The same message could be delivered in full sentences but the emphasis might be lost both by context and ‘look’.
In terms of format, submit it for copy editing according to the requirements of the editor. These days most will want the manuscript to be digital in an easy to read font. Although it is simple to change a digital file in dozens of ways, make it as easy as possible for the guy at the other end. Some editors still prefer hard copy. If no specifications are given for hard copy format, use these: one inch margins all around, double spaced. Helvetica or Times New Roman font. Print on a non-shiny, white, 20 pound, paper. Package well for mailing. Damaged copy may be impossible to edit.