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?

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What's the best way for a Schemer to learn Common Lisp?

Read Paul Graham's ANSI Common Lisp, that is mostly an extract from SICP, adapted to realities of CL. You won't learn much new, but will see how CL relates to Scheme.