Web typography
Typography exists to honor content.
— Robert Bringhurst, The Elements of Typographic Style
The web is not really suited to interesting typography but is still possible to achieve elegance and readability.
Font choices
All browsers allow users to choose their fonts and ignore yours. Plus there is no guarantee your preferred font will be present on the user's PC, in which case the browser willl choose a similar one based on the font's family - serif, sans-serif, cursive (handwriting style), monospace (typewriter style).
A good (business) choice is a sans-serif font (no curly bits) like Verdana, Helvetica or Arial. Serif fonts are handy for titles, and to feature small pieces of text.
Text size
Reading on the screen is slower than on paper. Small text makes a page even harder to read. You will be well served by presenting your content in 80-100% of the browser's standard size.
Small text makes page layouts look better in client presentations. Modern browsers allow the user to change the text size, so something of a mistake to make how the page looks depend on text taking up a certain amount of the display.
Achieving elegance and readability
The web presents a special problem: you can't control the final display, and need to allow for variability, eg screen size, text size, quality of display etc. therefore you are in the business of proposing how a page will look.
- Headings: Have some. Give some emphasis to headings, so they assist page scanning. A style for main headings, and one or two sub-headings is enough flexibility to cover most situations. They don't have to be huge. Downstyle typing for titles (only the first word and any proper nouns) is more readable on the screen.
- Main text content: Select a (sans-serif) text style in 80-100% the standard font size with a line height 1.4 to 2 x standard setting.
- Lists: Arrange for lists within lists to appear in the same text size (the default display will make them smaller).
- Case: Capitalisation creates monotonous rectangles on the screen. For titles only, where it can add emphasis and convey strength, or perhaps an OCCASIONAL word here and there.
- Justification: Kept it left with a ragged right edge. You can justify text on web pages but the rendering is unsophisticated. Right justification seriously reduces readability, but may have a role if used sparingly. Centering chunks of text is for wedding invitations not webpages.
- Links: Reserve underlining for links. This is a simple and well-understood way to make them stand out. Colour-wise, they need to be instantly recognisable. Having them go bold, italic or change size etc when you hover on them introduces scren wobble (because extra space has to be created for the effect).
- White space: Provide a decent amount of space between chunks of text, but remember vertical space on the screen commands a premium (less vertical spacing = more content visible).
- Emphasis: Reserve underlining for links. Prefer bold as a rule. Italics are hard to read on a screen because ther are not enough pixels to make a decent italic display.
Elsewhere: Why Web Users Scan Instead of Read by Jakob Nielsen, the daddy of website usability, Typography section in the classic Web Style Guide from Lynch and Horton, where I found the top quote at the top of this page.