The most important thing I learned from Overcoming Bias was to stop viewing the human mind as a blank slate, ideally a blank slate, an approximation to a blank slate, or anything with properties even slightly resembling blankness or slateness. The rest is just commentary - admittedly very, very good commentary.

The posts I associate with this are everything on evolutionary psychology such as Godshatter (second most important thing I learned: study evolutionary psychology!), the free will series, the "ghost in the machine" and "ideal philosopher of perfect emptiness" series, and the Mind Projection Fallacy.