I'd recommend any/all ofhis books - they are very funny and very clever.
However, many people have difficulties with 'getting into' them; I had that problem to start with, myself.
Lords and Ladies is one of the Witch books and they are probably easier to read than most so if you have never read any of his books it might be a good one to start with.
The books are all full of quotes from other books, misquotes from other books and clever puns and one-liners so I usually find something new every time I re-read them.
There is a web site which lists all the sources from which he has taken material - called 'the annotated pratchett' - google will find it if you feel the need to check his sources.
minnie la rose
http://members.iinet.net.au/~ploke
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