I call the sixth error of self-publishing, font abuse. That not as prevalent and it once was, font abuse is using multiple font styles, with varying point sizes throughout a manuscript.
The author may view this as creative formatting, but the only thing it accomplishes is irritating the reader. At best, this barrage of fonts slows readers down; at worst, it causes them to stop reading altogether.
In one self-published book, the first page used four different fonts and even more point sizes for those fonts. There were words in bold, italic, and uppercase. It was a nightmare to read. Hoping it was an anomaly, I turned the page: two fonts, four point sizes, and some more italic formatting.
The variations in font shape and size repelled me. I didn’t want to read further. If I’d have pushed through, I’m sure a headache awaited me.
This was font abuse at its worse—and a telltale sign of a self-published book.