Okay, so you've proofed your work. What more is there to do? Aside from doing every bit of research you can find to do in order to make your content the best that it can be, there is one thing I do. I look at the appearance of the text. Yes, I said appearance. I reduce the magnification of the document down to 10%. This size is helpful mostly with the placement of pictures; it allows you to see at a glance if your pictures are aligned properly and not breaking across a page. Any red or green lines are also visible, just in case you missed something.
Another thing to do with appearance is to begin a new chapter on a new page. This may not be such a big deal. I don't own an eReader, and I've heard that some of them don't have 'pages' so much as a constant scroll down. Pardon me if this is incorrect; I've seen only one up close and it did have 'pages'. At any rate, starting each chapter on a new page makes your document cleaner.
Now, back to appearance. Here is where 25% magnification can help you see how your document looks. I aim for approximately ten pages per chapter. This is not a hard and fast rule, just something I aim for. If my chapter is way more than that, I try to find a place where it can be broken; if it is too short, I look to add content, or maybe it can be melded in with another chapter. At 25% magnification, there are eight pages across a full screen. This allows me to spot the chapter headings, and I should have one on almost every line.
Most writers who work with Word know how to insert a page break before a chapter heading, but this is something I had to learn on my own. Before I learned that little trick, I used the 25% magnification quite often to make sure I had my chapter headings where I wanted them. For those of you who don't know how to do that, go to 'insert'; in the drop-down window you will see 'break' and from there you can choose several kinds of breaks. A page break will start whatever is after it on the next page, and even if you add content before it, enough to fill the page, your break will move along, pushing your next chapter heading to the beginning of the next page. There is also the section break. This is very helpful in numbering your pages. Using section break allows page 1 to be on the beginning of your story, not on your title page, which makes your table of contents work properly too.
In my latest and longest work in progress (it keeps getting shelved as other projects come up), I have two levels of chapters. As per the plan, there will be 16 main chapters spanning ten years of my character's life as a druid. Each main chapter has approximately 10 secondary chapters covering incidents and events along the way. Yeah, this one is a long one, and it has me worried. It's almost in a format to be a television series. At this point, I'm near the end of the second season of four, possibly five seasons, and if we cover each season as one year within the book, it'll be ten seasons - now wouldn't that be fun?
One thing that makes navigating this, and all of my documents, is the 'document map'. To make it work, your chapter heading need to be actual style headings, and you can modify your heading so they appear the way you want, and are consistent. These headings are another thing that makes your table of contents work. Another little thing a document map is good for is if you happen to number your chapters, you can easily see if you've skipped a number or repeated a number. Of course this will show up in your table of contents too.
In my opinion, appearance is every bit as important as good spelling and grammar. Inconsistent formatting, font and size is something a reader will notice.
Do you check your document's appearance, or do you leave that up to your publisher?