You have already ensured that you use features like page size, page breaks, automatic Table of Content and automatic page numbering. But there are some micro level issue with formatting you might face, when you are trying to give consistent look and feel to the content. Some of the tips here may help.
Line Spacing:To achieve the right and consistent line spacing in the book, select the relevant text, right click and select "Paragraph". "Indents and Spacing" tab should open by default. If it does not, click on that tab. In the "line spacing" choose the suitable option. The important ones are "Single" and "Multiple". Most of the time you would choose "single" spacing. If however, you do want to change it to something else, you can select "Multiple". After selecting multiple, you can put the multiple value in the box next to it. Enter 2 for double line spacing, 1.5 for one and half line spacing and .75 for 3/4th line spacing. If despite selecting a consistent line spacing from here, any parts show a different spacing, check the spacing options called "Before" and "After". Make sure it is zero in both.
Use "Paste Special" for pasting web content:If you are copying content from your website or blog, most of the time you would have to reformat it to suit the formatting of a book intended for print. One thing that makes this reformatting easier is a feature called "paste special". Instead of directly pasting the content, select "Edit -> Paste Special" and select "Paste Unformatted Text" from there. This would paste the content in the default format of your document. You would still have to clean it up and format it further, but this would reduce a lot of work. In word 2007, "Paste Special" can be found by clicking on the Dropdown of "Paste" on the left side of "Home" tab.
Removing Hyperlinks:This also pertains mostly to the content pasted from web. However, sometimes if you type a URL or an e-mail address, MS Word automatically converts it to hyperlink. Do remember to remove these links. To remove a link, right click on the word/phrase having the link and click on "Remove Hyperlink".