Polish (the verb, not the nationality)
Your ideal should be to submit a manuscript that is ready for publication: its grammar should be unimpeachable, its formatting precisely in line with the journal's preferred style, and the argument clear and compelling. Not only will this suggest to an editor a level of competence and diligence, it will make his/her job that much easier, as each round of revisions requires time and increases the possibility an editorial turn-over will occur before your article is assigned to an issue.
The process of preparing your submission starts well before the final proofreading, however. Make sure you know the house style for the specific journal you're planning on submitting to. Theatre Journal, for example, requires authors follow the Chicago Manual of Style (15th edition), use endnotes rather than footnotes, submit Microsoft Word files of between 6,000 and 9,000 words, and only include the author's name/institution on the first page of the manuscript. (Submissions that fall outside the word range or that do not follow the specified style are not read.) Alternately, Theatre Survey accepts submissions of 25-40 pages in length, requires an abstract, and specifies fonts and pagination styles. And Theatre Topics accepts submissions of 4,000 to 6,000 words and asks that the title page be submitted as a separate file. It's hardly a promising first impression if an author hasn't even taken the time to read a journal's guidelines before submitting.
Similarly, the manuscript should be free from grammatical errors, incomplete or incorrectly formatted citations, or quirky formatting. Run it by your advisor for feedback on content and mechanics, and find someone whose writing ability you trust to proofread if your advisor doesn't meet that criteria (or even if s/he does, it can still be helpful, as more eyes are usually beneficial). Again, initial impressions are key, and you don't want the editor's first thoughts on opening your file to be exasperation as she is faced with a page shot through with words underlined in red squiggly lines, or as he is forced to dodge dangling participles or leap over a veritable minefield of superfluous commas. (Or, for that matter, to slog through an indulgent jumble of strained metaphors, as in the previous sentence ;)