Thank you. I have come across your posts about moving from Python to CL, and the work you've been doing with the cookbook and other libraries is very much appreciated.
Your recent efforts might be one of the reasons there is a little bit of Lisp hype on this forum lately :-)
If you want true common lisp SBCL is probably the most universally known, and yeah everything I've read indicates one of the first things you should do is download and run the quicklisp setup so you have it working with your environment. Though it is funny how Hard Way did it during initial setup but then hasn't used it at all and I'm a chunk of the way through. Even as a beginner book I'd probably briefly touch on packages because it is so important to modern development.