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.
Use 20 lb white bond paper. Double space everything and type on one side only. Use 12 point Times New Roman typeface and signify paragraphs by indenting 5 spaces.