A handy guide:

http://practicaltypography.com/typography-in-ten-minutes.htm...

Typography is a big topic, but a good introduction is "Stop Stealing Sheep and Find out How Type works" by Erik Spiekermann [1]

It is an especially good read for non-designers, though I've given several copies to interns.

[1] - http://www.amazon.com/Stealing-Edition-Graphic-Communication...

More simple statements:

* The longer the line the more space between lines

* Do not to mix font families

* Do not use fancy fonts

* You should probably give things more space around

* Use left aligned text, not justified

Of course, such rules are too simple. They have exception, implications, corollaries, and conflict with each other. Balancing this out is the art of typography.

Jason Santa Maria's new book from A Book Apart, On Web Typography, helped me as a non designer really understand good typography. I still cannot necessarily create good typography like the masters but I can now recognize it.

http://www.abookapart.com/products/on-web-typography