be very careful about using non standard materials for verbal. you can learn the concepts from any book, but be careful about the problems that you practice with.
if you do not have a fairly good background in verbal concepts, i strongly suggest taking the help of a tutor or taking a prep class.
if you need practice problems, use the Official Guide, ETS paper tests and the LSAT's. (in that order). in the LSAT's, i recommend the LSAT Superprep , followed by the series of LSAT tests.
thanks
Praetorian