Some simple rules to follow for improved typography (web or print), from Fred Design:
- Don’t use too many typefaces (not more than 3).
- Pay close attention to the hierarchy.
- No more than 4 font sizes, preferably 3.
- 8-10pt for body copy (definitely not above 12pt).
- Use simple, legible typefaces.
- Keep leading in mind (a little above the font size, slightly below the auto setting, no overlapping).
- Keep kerning in mind (no overlapping).
- Emphasise subtly (bold, italic, underlined or a darker shade).
- No caps in body text.
- Always align to a baseline.
- Flush left, ragged right (keep text left aligned, not justified).
- Between 6 and 12 words per line (as a general, flexible rule).
- Hanging punctuation marks and bullets, not indented.
- Experimental: use Fibonacci numbers for point sizes.
Similar and worthwhile: Mark Boulton’s Five simple steps to better typography.
Don’t forget these ebooks, either!