Some items to check include the following:
Word Count: Each publisher has a very good reason for its maximum word count. No matter how well written a novel, submitting a 100,000 word story to a publisher whose maximum word count is 80,000 means one of two things: 1) the author cannot follow instructions; or 2) the author does not care for the rules. Either way, the author does not make a good impression.
What Genre Does the Publisher Print? Pelican Book Group has three imprints, White Rose Publishing, Harbourlight Books, and Watershed Books. Each imprint has specifics about the genres represented by those imprints. An author should not only check the submission guidelines carefully. He should also have an idea of the style the publisher seeks. This requires reading the books printed by that publisher.
Are There Situations the Publisher Will Not Allow in Its Novels: Each publisher has an idea of what will offend its readers. Some of these issues vary from publisher to publisher, so it is always a prudent idea for an author to look carefully at the "Thou shalt nots" in the publishing guidelines before submitting.
The Nitty Gritty: Careful attention to grammar and punctuation is often overlooked in a query letter or a proposal when these items are generally the editor's first impression of the author.
Recently, a New York Times bestselling author told me that she does not worry about punctuation and grammar. She leaves those up to her editor. An author with a proven record of millions of copies sold might be able to get away with this, but no matter how well known, how successful a writer, a knowledge of punctuation and grammar exhibited in a submission is often a factor in acceptance. A well-polished manuscript's correct punctuation and grammar are sometimes overlooked because with those errors out of the way, the story will get the most attention. Rest assured, though, that a manuscript filled with grammatical errors and incorrect punctuation, will always garner the editor's attention. And as an aside, I'm currently reading a book by the bestselling author mentioned above, and the lack of attention to grammar and punctuation shows the editor's lack of attention to detail, and this reflects poorly upon the author.
When preparing your manuscript for submission, don't forget to self-edit the proposal down to the smallest detail.