If you like reading The Amazing Randi, then you must read the Ninth edition of The Skeptic's Circle.

St. Nate got some great posts on how to apply critical thinking on Ghosts, Aliens, Psychics and Stars, Bad Medicine, Pseudoscience and more.

The rules have tightened since previous editions of The Skeptic's Circle (you can read why here and here), but we still have good reading on skepticism and critical thinking. And I highly recommend you to read it all.