I use CL, but I also know Scheme.
Everyone should read their SICP and in the course of it, they will also read the lambda papers and the rnrs'es, thus learning Scheme.
CL is great for actual work as the language is large, there are a lot of libraries and portability is great across a wide variety of implementation. You'll learn CL by reading Practical Common Lisp, PAIP, the Hyperspec and CLTL2, AMOP (The Art of the Metaobject Protocol) among others books which I could list, but you'd be better searching using /prog/scrape for some of these keywords as you'll be led to more complete answers which I'm too lazy to give right now as they've been asked too many times.
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Anonymous2012-04-24 19:12
CL is diarrhoea.
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Anonymous2012-04-24 21:22
I love Scheme because the earlier revisions where simple. You use common lisp if you need full libraries of code before you do your work. I prefer to work in Scheme whenever I'm doing prototype work and I use CL whenever I want to implement a system through combining existing code libraries.