Sorry, this page is still Very Much IN PROGRESS! The main idea so far is, use a fairly normal typeface (like Roman, Helvetica, Courier, etc.), in plain black, and don't go overboard on the special effects, such as italics, bold, underline (especially on the web, 'cuz it looks like a link -- did you instinctively try to click it, or put your mouse on it to see what URL it leads to?), making text bigger or smaller, etc. Judicious use of effects can help emphasize specific points, or just make the whole thing not too plain. Too much, however, is just gaudy.