Here’s some from an Acquisitions Editor these past 20 years. I do magazines now, and read a thousand manuscripts a year to publish maybe 50. WHen I did books, I read 800 or so manuscripts a year and published 30. An acquisitions editor who doesn’t learn to rapidly separate wheat from chaff will quickly flounder.
The first cut almost always comes on the cover letter. It should be one page. Let me repeat that: One Page. It should tell briefly and concisely, and in absolutely perfect English (or whatever language is native for you and the publisher), what you’ve written and why, with a line or two about who you are and what qualifies you to write about this specific subject.
Don’t tell me how good you are; I’ll be the judge of that. Don’t tell me it’ll be a bestseller; the market will judge that. Don’t tell me what your friends thought of it; I don’t know your friends. Just tell me what so captivated you by the subject that you felt compelled to write a whole book about it. On one page.
If you have significant publishing credits (i.e., not a supermarket shopper or a free magazine, but something significant, whether regional or national or local, little literary or big-time slick), list them on a separate sheet of paper. If you have reviews, list these on another sheet of paper, with photocopies being preferred to transcription.
All this is just to get me to read your manuscript. And to tell you the truth, most slush-pile submissions never make it past the cover-letter phase, for the reasons listed above. If your cover letter is all self-congratulation and empty puffery, and ungrammatical to boot, what’s that say about the manuscript itself? It says, to every acquisitions editor I’ve ever known: Next envelope, please.
As for the manuscript–whatever the publisher asks for in its guidelines: typically double spaced, one-inch margins, 12-point type, pages numbered.
The last tip on surviving the slush pile: Send it to an actual person, not just the publisher. Got some recent books you really like, and that are similar in tone and approach and subject matter to what you’ve written? Call their publisher, ask for the name of the editor who acquired those books, and send it to her. For God’s sake don’t ask to speak to him or her. We don’t have time to talk with aspirants. We barely have time to talk to the authors already under contract.
But packages addressed to a specific editor tend to get read by that editor. Packages addressed generically to the publisher (all this assuming you don’t have an agent, which, because you’re asking formatting questions, I assume you don’t) get read by whoever’s desk they happen to flop on–often an intern or a low-level sub-ed so overworked he or she is just trying to make it through the pile.
Good luck. It does happen, you know.