- The Elements of Typographic Style by Robert Bringhurst,
- The Elements of Style by Strunk and White, and
- The Chicago Manual of Style.
While I'm on the topic, Edward Tufte's three-part series on visual explanation is also great.
...and my favorite pet peve: If you mean “to” by a dash, as in “110”, use an en-dash (– in html, “--” in TeX). Otherwise you get this ugly thing: “1-10.”