[georgeolivergo]

In addition to reading archives of comp.lang.lisp, I recommend exploring Lispforum.com, planet.lisp.org, common-lisp.net/pipermail/pro, and searches such as https://github.com/search?q=common+lisp.

As a new lisper coming from Python, my impression is that while there is a ton of good reference material going way back, it's also important to find where the contemporary work and discussion happens, what the current best practices are, and so on.

For books for the beginner to intermediate programmer, I would go with PCL and Successful Lisp in tandem; for cross-platform implementations SBCL and Clozure (formerly OpenMCL).

And of course, this: http://abhishek.geek.nz/docs/lisp-answers/.