We have a Nook rather than a kindle, so the formats are slightly different and the capabilities aren't exactly the same, but close enough. I've found that the most important thing is not having hard linebreaks and things like that in there, which can really mess up the flow of text. Chapter anchors are nice, but since I tend to read straight through and the Nook remembers where I left off on each book, it is not much of a problem for me if they don't. Commercial ebooks have all the illustrations and graphic layout items, which seem to work well even if you shift the typeface and text size.