Only rarely do you see such a well written article with so many clued in concepts as this article in Seed Magazine pointed to below. I heartily recommend that you read it and if you don't understand it use a dictionary. You will save yourself many a heart ache by understanding first principles of the real world!
The real world is non-linear and so the old linear math of economics classes have to be re-written into non-linear expositions and contain many more real world exposures. Understand what randomness is all about. Realize that a fourth dimension, or possibly more, invade(s) our three dimensional world and that/those dimension(s) obeys(s) mathematics that is non-linear. Think fractals!
On Early Warning Signs
http://seedmagazine.com/content/article/on_early_warning_signs/
(via Instapaper)