Fresh from WordCamp Phoenix 2012, Lance Willett who works for Automattic and is part of the theme wrangler team gave a great presentation for beginners on how to navigate the vast landscape that is WordPress themes. He covers the gamut such as where to look for themes, commercial themes, things to consider before using the theme on your site, etc. This presentation is truly for the beginner as it has nothing to do with coding. Nice job Lance.