Do use 9-, 10-, 11-, or 12-point type for optimum legibility in printed text.

Do use 11- or 12-point type if the typeface you prefer has a small “x-height” (small lowercase letters).

DON’T use 6- or 7-point type for regular reading material. If you must use 8- and 14-point type, use them sparingly as these faces slow reading speed significantly.

Do use a serif typeface for text matter, as style choices and size permit. Readers generally prefer serif styles, such as Times Roman, Garamond, Goudy, etc.

Do use a sans serif typeface, such as Helvetica, for headlines, visual presentations, and signage or for text matter if it fits the tone or mood of the message.

Do use a typeface, whether serif or sans serif, that has a medium body weight—not light or bold—when selecting type for text matter.

DON’T worry about serif vs. sans serif for reading speed—the difference is insignificant.

DON’T pick typefaces for text matter or headlines if they fall into the following categories: script or calligraphic styles (Old English, Cloister Black, Wedding Text, etc.); hand lettered (Brush, Dom Casual, etc.); and “cutesy-pie” type styles (Cueball, Hobo, etc.).

Do use Roman type of medium body weight (Helvetica Regular, Times Roman, Palatino, etc.) for text.

Do use bold type for emphasis—but sparingly. Bold type often works best for visual presentations (slides, videos, etc.) and for signage.

DON’T use italic type if at all possible; readers dislike it strongly because it is hard to read.

DON’T use bold type for long sections of text matter; it tires the eye.

DON’T use extremely light type (Helvetica Light, Avant Garde Light, etc.). It does not contrast sufficiently with the background.

Do try to gauge line length by the number of words per line, or by the number of characters and spaces per line—10 to 12 words per line, or between 35 to 55 characters and spaces per line.

Do use narrower line widths for small type, i.e., use 12- or 14-pica (2- to 2.5-inch) lines for 7- to 8-point type.

Do use moderate line widths for 9- to 12-point type, ranging in width from 18- to 24-pica (3- to 4-inch) lines.

DON’T use very narrow line widths (1 to 11 picas) for any size of type.

DON’T use very wide line widths (more than 25 picas or more than 55 characters per line).

Do lead (line space) between lines of 9 to 12 point type, using either 1-, 2-, 3-, or 4-point leading. (The amount of leading used is a matter of personal taste.)

Do use more leading for heavier typefaces and for longer line widths.

DON’T set type solid (no leading); readers dislike solid text matter and read it more slowly.

Do choose which style—justified or flush left, ragged right—you like best since all research says they are equally legible for normal readers.

Do consider flush left, ragged right when children or slower-paced readers are involved. They scan it better.

DON’T set text type flush right, ragged left, or centered line for line. Readers dislike it.

Do set text matter in lowercase, using uppercase only for the first letter in a sentence and for the first letter of proper nouns.

Do set headlines either “up-style” or “down-style.” (Up-style capitalizes the first letter of nouns and verbs, and lowercases prepositions and articles; down-style capitalizes only the first letter of a headline and any proper nouns.) Both styles are equally legible.

DON’T set any text matter or long headlines in all capital letters. The use of all caps significantly reduces reading speed and uses 25 to 35 percent more space, depending on the typeface.

Do select ink and paper on the basis of maximum contrast between the two. There should be a difference of at least 65% between the density of the type and the color of the background on which it is printed. (Black ink on white paper is most legible, followed closely by black ink on yellow stock.) Many of these same principles apply to visual presentations and signage.

DON’T use darker paper colors for text material, and DON’T print darker background colors behind type.

DON’T use light or medium ink colors for text matter.

DON’T worry about which light-colored paper to use. Research indicates that papers in such colors as yellow, ivory, light green, etc., have little effect on legibility or eye strain when black ink is used.

Do use reverse type for visual presentations (slides, videos, etc.) and signage for improved legibility.

DON’T use small type (9 point or less) in reverse form (white on black background) for text. Use larger typefaces sparingly in reverse. Readers show low preferences for text type in reverse, and they read it more slowly.

Do set numbers as Arabic, rather than Roman, numerals, using Old Style numerals when possible. (Old Style numerals have ascenders and descenders that make them more legible and more readable than Modern Numerals.)

DON’T set numbers written out in word form. Numerals take less space and are read faster than words.