The best LISP textbook I know of is
Guy L. Steele Jr. Common LISP: the Language , The second edition. Digital Press. 1990. Also called Cltl2.
The first edition is easier to read; the second describes a more recent standard. (The differences between the two standards shouldn't affect casual programmers.)
A book by Dave Touretsky has also been recommended to me, although I haven't read it, so I can't say anything about it.