Originally Posted by Holly Lisle

You have two choices with manuscript formatting -- you can either format first or format last. I format first -- that is, I do the whole novel in exactly the same format in which I will submit it. It uses more paper for print-outs, but I can copyedit my work easily, and I don't have to mess around with it later -- when the words are done, so is the formatting.
Once you've decided when you're going to format, however, the next question is ... how?
I use two formats -- one for novels, and one for short work, both fiction and nonfiction. I have never had a complaint about my formatting, I have never had work bounced for formatting, so I know that both of these formats are professionally acceptable. These are not the only correct manuscript formats out there. There is, contrary to beginner myth and legend, no one single correct format, nor even one single correct typeface.
I'll give you both formats that I use here, and if you decide to use them, you can rest comfortable in the knowledge that, no matter what else happens, your work will not be rejected by a professional market because of its format. (Unless, of course, your particular market specifies a specific format. I know of no pro markets that do this, though amateur markets seem to be rife with this sort of 'our way or the highway' nit-picking.)

Here are the formats:

Novel:

• Page Information
  • Margins -- 1.5 inches all the way around
  • Font -- Courier, Courier New, or other clean monospace serif font from 10-12 pt. (I use 12 pt. Dark Courier.)
  • Line spacing -- Double-space
  • Paragraph indent -- first line, 5 pt.
  • Header -- right justified, contains the following information:
    
    Last name/ TITLE/ page#
    
    A header does not belong on the cover page. Start headers on page one of the actual manuscript.

Cover page -- depends on whether you're agented or not.

• Unagented:
  • Contact information -- Name and address, phone number and e-mail address in the top left corner of the page, single spaced, left-justified
  • Title -- centered, just above the middle of the page
  • by -- centered and one double-spaced line beneath the title
  • Name or pen name -- centered and one double-spaced line beneath the word by
  • Word count -- centered and rounded to the nearest thousand, one double-spaced line beneath your name or pen name
• Agented:
  • Title -- centered, just above the middle of the page
  • by -- centered and one double-spaced line beneath the title
  • Name or pen name -- centered and one double-spaced line beneath the word by
  • Word count -- centered and rounded to the nearest thousand, one double-spaced line beneath your name or pen name
  • Agent's contact information -- Name, business name, mailing address, phone number (e-mail address if you have the agent's okay first), left justified, single spaced, bottom of the page

First page

• Header -- should be in the upper right-hand corner of the page, and page number should be 1.
• Chapter header -- can be anywhere from one to six double-spaced lines down from the top of the page, and can be centered or left justified. You can title your chapters, or just write Chapter One or Chapter 1.
• Body text -- drop down two double-spaced lines to begin your story.
• Scene breaks -- drop down two double-spaced lines, insert and center the # character, drop down two more double-spaced lines, and begin your new scene.
• Subsequent chapters -- start each chapter on a fresh page. Keep chapter formatting and titling consistent with your first chapter.

Short work

• Page Information
  • Margins -- 1.5 inches all the way around
  • Font -- Courier, Courier New, or other clean monospace serif font from 10-12 pt. (I use 12 pt. Dark Courier.)
  • Line spacing -- Double-space
  • Paragraph indent -- first line, 5 pt.
  • Header -- right justified, contains the following information:
    
    Last name/ TITLE/ page#
    
    A header does not belong on the title page. Start headers on page two of the actual manuscript. First labeled page number should be 2.

Cover page

• Do not use a cover page with short work, either fiction or non-fiction

First page

• Contact information -- Name and address, phone number and e-mail address in the top left corner of the page, single spaced, left-justified
• Word count -- top line, right justified (you'll have to do this with a table if you're working with a word processor), either exact count, or rounded to the nearest ten
• Title -- drop down four double-spaced lines, centered
• by -- centered and one double-spaced line beneath the title
• Name or pen name -- centered and one double-spaced line beneath the word by
• Body of the story or article -- drop down two lines and begin.
• Scene or section breaks -- drop down two double-spaced lines, insert and center the # character, drop down two more double-spaced lines, and begin your new scene.

Second and subsequent pages

• Header -- should be in the upper right-hand corner of the page, and page number should be 2.
• Body text -- begins on the first line, doublespaced throughout

Originally Posted by woodcut.evolution

I was using double sapces between sentences before I knew it was a rule (even if it's a not always used rule). I don't think I could give it up if I wanted to.