Fields Medal winner Terry Tao put together a page on his blog titled Career Advice.

He writes:

Here is my collection of various pieces of advice on academic career issues in mathematics, roughly arranged by the stage of career at which the advice is most pertinent (though of course some of the advice pertains to multiple stages).

Afterward he give advice for students in primary school, high school, college, graduate school, and those in a postdoctoral position. He concludes with links to other such pages that were written by others.

[via Trivium]