Common Lisp for Schemers

What's the best way for a Schemer to learn Common Lisp? It seems like Scheme itself is a more beautiful language, but the efforts made by many implementations to make Scheme useful "in the real world" lead to a big ball of mud™. Does Common Lisp avoid this problem? Should I keep trying to learn different Scheme implementations instead until I find something I like?

OP here, thanks for the read. <3

>>8
Thanks for this, I'll pick up the book sometime. I don't really care if the language is antiquated, I already like Lisps enough that I feel like I should learn it.