Rules of Typography

Typography is an important element to design, communication and information delivery. It is everywhere yet we rarely recognize it.
Legibility = Classical, time-tested typefaces have the best readability
Serif = Reads best at smaller sizes; can be complimentary
Variance = Adds flavor, but too much can confuse the reader
Definition = Draw attention to certain words, fonts that are too similar means lack of clarity
Alignment = Align words considering eye flow -- left alignment reads easiest
Integrity = Distorted and warped works hurt the eyes and makes it harder to read
Weight = Different font strokes to create a sense of balance, mostly heavy or light

The 19 Rules of Typography

1. Choose classical, time-tested typefaces for optimum legibility.
2. Be mindful not to use too many different typefaces at once. The reader should be able to determine what I and isn't important through the font.
3. Avoid combining similar faces. This will reduce the emphasis of the text.
4. Text set in all capital letters severely hinders reading.
5. Use sizes that aid readability. The best size is 8 to 12 point for text 12-14 inches in length.
6. Avoid using too many sizes and weights at the same time. Two different sizes at most is recommended.
7. Use text types of book weight (not too heavy or too light).
8. Use type faces of medium width.
9. Use consistent letter and word spacing to produce an even, uninterrupted flow.
10. Use appropriate line lengths or ligatures. 
11. Use line spacing that easily carries the eye from one line to the next.
12. Use a flush left, ragged right (left aligned, right varies in length) alignment for optimum readability.
13. Strive for consistent, rhythmic rags (right edge of left-justified paragraph).
14. Clearly indicate paragraphs, but be careful not to upset the integrity of the text.
15. Avoid widows (word or short line at beginning or end of paragraph) and orphans (single syllable at the end of a paragraph) whenever possible.
16. Emphasize elements within the text with discretion and without disturbing reading flow.
17. Always maintain the integrity of type, and avoid arbitrarily stretching letters.
18. Always align letters and words on the baseline.
19. When working with type and color, ensure sufficient contrast between type and background.