I've been trying to get my new writing craft book, Advanced Plotting, on the market. Yesterday I received the proof copy from CreateSpace. Had it been fine, I could have officially published the book. Unfortunately, I discovered a problem with my line spacing. The bottoms of hanging letters such as g and p were getting cut off. You couldn't tell in the Word document, but you could in the PDF I'd sent to Amazon for printing.
This is one of the challenges of self-publishing -- you're responsible for all the details. I thought that since I'd previously done the layout on two books, I could manage this one. In fact, I used a previous book as a template. But I had accidentally used the font from my chapter headings (Adobe Caslon Pro) with the line spacing from the body text (Georgia). The Georgia font is fine with a standard 13.3 line spacing, but Adobe Caslon Pro needs a minimum of 14.2. After I realized my mistake, I remembered that I had changed the font to Georgia for The Eyes of Pharaoh's body text because Adobe Caslon Pro needed so much extra space. (I've now made a note of it for future reference.)
I spent several hours reformatting the manuscript. It wasn't a simple matter of just changing the line spacing. I had over 30 sections, each with a different font and line spacing for the heading. If I'd changed the whole document at once, it would have messed up all the headings, plus the title pages. I had to deal with each section separately. As an additional complication, the new line spacing meant each paragraph took up more space. But I didn't want to change the page numbers, because not only did I have the page number set in the table of contents, but within the text I reference different essays by page number. I had to make adjustments to make sure each section started on the same page as before.
I'm sharing this as an example of some of the specific challenges you face when publishing on your own. Of course, you can hire somebody to do your interior layout. You may want to do that if you have enough money and don't have a graphic design background. Otherwise, be sure to plan enough time to get the proof copy of your book and study it carefully.