Here is Rebecca's handy dandy guide to manuscript formats. While different publishers have different guidelines, this format is generalized and is often acceptable.
Margins: 1 to 1 1/2 inches
Title page: No page number Leave the upper left corner blank. Upper right: wordage
Drop 16 lines; type TITLE in all caps Drop 2 lines and type: the SERIES TITLE-all caps (if appropriate) Drop 2 lines and type Book # (if appropriate) Drop 2 lines and type A book (or novel) By Drop 2 lines and type your name Center these lines
Down in the lower right hand corner type your agent's name , address , etc.
On the next page and every page thereafter you need a header. Flush left: The TITLE of the book in caps, then two dashes then your last name, initial cap. Put the page number flush right.
Each chapter should begin on a new page. Move 1/3 of the way down the page to type the CHAPTER number (All caps and a number)
Drop about 8 lines. Indent for text and begin the chapter.
Double space everything and use 12 point Times New Roman typeface and signify paragraphs by indenting 5 spaces.