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?

>>32
function0 :: A -> B -> C
main = do
 function1 <- return $ function0 x -- created a new function at runtime
 return $ function1 y -- called it at runtime