The base measurement is the distance between the base of a letter and the base of one in the line immediately below. Line length should be no less than 40 characters and no more than 60. This can be awkward on an A4 page. To keep the type size within the recommended ranges, you ll need two columns or very wide margins. Justify lines Justification increases comprehensibility, and is preferred by the majority of readers from a wide range of backgrounds.
Ragged right is the next best.
Text set ragged left, or following a curved margin, as used in many advertisements, is hard to read, and most people don t bother. Use generous margins Traditionally, hard and softcover books have been printed with around 50 percent of the page covered in type. Comprehensibility drops if 60 percent or more of the page is covered. The layout of the page should follow the principle described by Arnold as reading gravity . In the western world, we start reading from the top left hand corner and work our way across each line, down to the next line and continue until we reach the bottom right hand corner.