The way a book interior is designed has a part in whether the book will sell or not. A customer will not read—or buy—a book that is designed in a way that is difficult to read. If the type in your book is too small, or the spaces between the lines are too narrow, many prospective customers will move on to another book. Your goal with book design is to create an interior that is inviting, pleasing, and easy to read. This involves good use of fonts, word spacing, leading, line length, and alignment. Here are some techniques that professional typesetters use.
Go to bookstores and peruse books in your category of interest. Take notes on the ones you find attractive, easy to read, and that appeal to you. Make sure it is appropriate for both the reader and the book. After all, fonts (like people) have personalities, and different designs will appeal to people of different ages. For example, if your readers are either very young or senior citizens, then choose a simple, well-designed font in a large size so the font can be read without strain.
Good choices for body copy are Garamond, Caslon, Goudy, Stone Print, New Century Schoolbook, and Janson Text 55 Roman. For your chapter heads and subtitles, choose a bold font with the right personality for your piece. Some common bold fonts are Helvetica Bold, Gill Sans Bold, Eras Bold, Univers Black, and Franklin Gothic Demi. Don’t use all caps for your heads, subheads or table of contents, because this style is difficult to read.
Leading is the space between lines of type. Leading is measured in point increments and specified in conjunction with the point size of the font. For example, 10/12 (read 10 on 12) is 10-point type with 12 point leading. In most cases, the leading of body copy should be about 120% of the point size of the text. (For example 10/12 or 12/14.4.)
Also make sure you set your leading in proportion to the line length of your text. In general, short lines of type require little or no extra leading but you should increase the leading as you increase the length of the line.
Using full-justified type makes a page look full and creates a tighter, more formal appearance than type that is not full justified. Most books are set with full-justified copy, because the reader’s eye can move more quickly across copy that has a consistent column width.
Length of Line (Column Width)
Reading many long lines of type causes fatigue. And lines that are too short break up words or phrases that are generally read as a unit. The length of line depends on the size of the type. A good rule of thumb is to set a line about 65 characters long. Set your column width to allow for at least a 1″ to 1.25″ gutter, and .5″ border for top, bottom, and outside edges.