Of course, if you are submitting to a Big Five publisher, use the related online submission guidelines. Each one is different. Be sure to follow it exactly. This may be the first test to see if your work is checked out further.
This post is more geared to the newbie Indie author.
In general, MSWord sets one-inch margins all around the standard 8.5x11" page. That works for e-books. Keep one version saved as clearly for online electronic offerings. If you are doing POD versions, follow their rules to allow for binding and offsetting pages. Save another version with POD noted in its document name.
Double space your work using the Paragraph menu line selection within MSWord.
Use MSWord's existing Styles for titles, chapter headers, subheads, etc. I believe the online venues require novels to have table of contents' references to each chapter, so go ahead and have that embedded in your work. When you use Styles, you are getting a TOC reference mark as well.
If you don't get a page break when using your chosen Style, and you need one (like with Heading 1 that I just used in another document), simply add it by using the MSWord Menu bar. Choose Insert, then Page Break.
You'll also see that the chapter headers include a page break before each, followed by a blank vertical space, then comes Chapter One, Chapter Two, etc. You can use the preset Styles within MSWord or you can edit one to make a new one to fit your preferences.
It is standard procedure to open your chapter and each time break with a flush-left paragraph. You'll note that my existing work does not encompass this, but I plan to follow this with each new future work. You'll have to manually backspace each such opener to override the auto-indent feature in your Ruler. Otherwise, set your Paragraph menu to auto indent the standard 0.5" for all paragraphs.
Use MSWord's Styles for italicizing and bold when adding emphasis to particular words within the text (to distinguish this from the bold/italics features within chapter headers and other such Styles). This would be used, for example, like here: He was just so beautiful.
Although MSWord has a Drop Cap feature, I understand it doesn't work well when professional formatters are preparing your Word doc to become a MOBI or EPUB version. They can add in a working drop cap for you. Otherwise, if you are doing it yourself, I'd avoid that for now until Word's option survives the upload processes.
If you've read these earlier related posts, all with "A US Copy Editor's Perspective" in the title, then you know to delete stray spaces, stray returns, manual tabs, etc. So for your title page, don't hit a bunch of returns to center your title in the middle of the first cover page. Again go to Styles. Or highlight your title, then go to the Paragraph menu, clicking on the down arrow in the bottom right-hand corner, and add 24 pt or more to the Spacing, Before. Leave Spacing, After, at 0 pt.
Save often while within MSWord. Even an otherwise unnoticed brownout can cause you to lose all your work. Then backup to thumb drives, disks, clouds, whatever you choose. But have two backups. I prefer one online and one on a thumb drive, in case my Internet is down. I also have printed out hard copies.
Stop to think of your 90K novel being gone, lost. Yeah, you could write it again. But it'd never be like the earlier one. Sure, it could be better; it could also be worse. But those words in that order are lost forever.
Do what you can right now to stop that eventuality from occurring.
These cover the basics. Now go forth and create!
Denise Barker, author + blogger + copy editor