Steemit is not so great for publishing books on.
The problem is that there is a maximum block size. So you have to break up your book.
Also, you have to host all of your pictures somewhere else. This can be a big problem if your book contains many pictures.

Steemit also doesn't have much in the way of formatting or placing pictures and text. It has enough, if the blog like format works for your book, but if more is needed it becomes unworkable.

Self publishing is easy, just make a pdf and upload it, have it printed on lulu. Marketing is the hard part.

So, what do you see yourself doing as for the marketing part?