The good guys from Smashing Magazine put together this great article on choosing the right typeface for the right job. Its a bit of a read, but well worth it. The great thing about this article is that it relates to any age group. They provide a set of principles, that if followed correctly, you will have the right typeface for your intended design.
In the article things like legibility, readability, design intent, aesthetics and mood are covered.
CHECK IT OUT!