The Official Guide for GMAT Review has detailed explanations for each question. It is in invaluable guide to understand the process of CR. Also, get the LSAT Superprep
. It has 3 tests with detailed explanations.
Another helpful way to master verbal this is to simply try to participate in forum discussions and take the time to explain your answer.
Others may have a different opinion, but I wouldn't trust Kaplan
too much with verbal.
Finally, stick to the Official Guide and LSAT in the early stages of your verbal prep. Learn the basic rules of sentence construction and CR. Make detailed notes of the errors you make.