To continue the list I started last week:
These things can be set up to happen automatically:
a) 1" margins all around. Top, Bottom, and both sides;
b) Double space lines;
c) Number pages, either top right or bottom right - you wouldn't believe the number of people who don't number the pages;
d) Header on every page, the order varies, but the header should contain the working title and the author's name (or at least last name);
e) Title page should include contact information in the lower left corner, (name, mailing address, phone number, email address, genre and word count);
f) It is my personal preference to have widows & orphans turned OFF, but probably most people accept either format. I think it looks less 'neat' with it turned on, though be careful about them. Google or go to 'help' in your software and learn what Widows & Orphans are -- especially if you are going to self publish and have to do the formatting. They really make a book look self-published (in a bad way);
g) Use a sensible font and pt size. Agents read such a large part of their day, make it easy on their eyes. Don't get cute with fonts. Besides, if it is online rather than in print, your font might not be supported by their software. Someone once used a font I didn't have (hard to imagine, I have tons of them) and it was $29+ to purchase it -- I passed.
These things have to be done manually:
a) One space (only) between sentences.
b) Insert page breaks at the end of a chapter so the new chapter begins at the top of a new page. Do not hit the 'enter' key repeatedly to do this, you have to use the page break function or you are totally screwed when you edit or do rewrites.
c) Center Chapter heading, use the center function, do not tab over and guess at the center. A computer might seem like a modern typewriter, but it behaves differently if you don't use the computer functions.
d) Use the tab rather than the space bar to begin a new paragraph.
e) Technically the first sentence of a Chapter is not indented. I ignore this because I begin my books (always) with a line of dialogue.
I'm sure I've forgotten a thing or two. I do these things automatically because I have done them for years. Sitting here looking out the window at the snow it is a bit harder to think of them for a list. Review their website, many agents and publishers list specific guidelines for submissions. These serve two functions, they want things that way and they want to see if you can follow instructions.
This stuff is for fiction mss, not for non-fiction...though a memoir is not fiction, it is done in a novel or fiction format.
Additions to this info or questions about it are welcome in the comment section. We're all in this together. Like Nick said yesterday, don't obsess - but do remember you are applying for a job as a novelist against tons of other applicants. Look sharp. Write well.