Reading is a habitual skill. What you read most often is easiest for you to read. This is why newspapers, magazines, and books are more or less standardized. Basic Book Design will teach you to make your document look conventional.

Breaking these rules usually makes your book harder to read. I.e., a book that looks "distinctive" and artistic is usually hard to read. Conversely, easy-to-read books usually look boring and conventional.

A good compromise is to design a distinctive and artistic cover, chapter titles, running headers, etc.; and make your text boring and readable.