The measure is the length of a line of type. To a reader’s eye, long or short lines can be tiring and distracting. A long measure disrupts the rhythm because the reader has a hard time locating the next line of type. The only time a narrow measure is acceptable is with a small amount of text. For optimum readability you want the measure to be between 40 – 80 characters, including spaces. For a single-column design 65 characters is considered ideal.A simple way to calculate the measure is to use Robert Bringhurst’s method which multiples the type size by 30. So if the type size is 10px, multiplying it by 30 gives you a measure of 300px or around 65 characters per line.
Leading is the space between the lines of type in a body of copy that plays a big role in readability. Correctly spaced lines make it easier for a reader to follow the type and improves the overall appearance of the text. Leading also alters typographic color, which is the density or tone of a composition.
3. Hanging Quotes
Hang quotes in the margin of the body of text. By not doing so a quotation mark that is flush with the text will interrupt the left margin and disrupt the rhythm of the reader. Hanging quotes keeps the left alignment intact and balanced therefore increasing readability.
4. Vertical Rhythm
A baseline grid is the foundation for consistent typographic rhythm on a page. It allows the reader to easily follow the flow of the text, which in turn increases readability. A continuous rhythm in the vertical space keeps all the text on a consistent grid so that proportion and balance are retained throughout the page, no matter the type size, leading or measure.
5. Widows & Orphans
A widow is a short line or single word at the end of a paragraph. An orphan is a word or short line at the beginning or end of a column that is separated from the rest of the paragraph. Widows and Orphans create awkward rags, interrupt the reader’s eye and affect readability. They can be avoided by adjusting the type size, leading, measure, wordspacing, letterspacing or by entering manual line breaks.
Giving emphasis to a word without interrupting the reader is important. Italic is widely considered to be the ideal form of emphasis. Some other common forms of emphasis are: bold, caps, small caps, type size, color, underline or a different typeface. No matter which you choose, try to limit yourself to using only one. Combinations such as caps-bold-italic are disruptive and look clumsy.
Always compose with a scale, whether it’s the traditional scale developed in the sixteenth century that we’re all familiar with, or one you create on your own. A scale is important because it establishes a typographic hierarchy that improves readability and creates harmony and cohesiveness within the text.
8. Clean Rags
When setting a block of text unjustified with a left or right alignment, be sure to keep the rag (the uneven side) balanced without any sudden “holes” or awkward shapes. A bad rag can be unsettling to the eye and distract the reader. A good rag has a “soft” unevenness, without any lines that are too long or too short.
Compiled from: http://www.smashingmagazine.com/