1. The Quant part:
I believe How to Prepare for Quantitative Aptitude for the CAT Common Admission Test by Arun Sharma. I actually read the 4th edition but I think 5th will also be fine. From my experience, CAT math’s is and will not be tougher or easier (interesting na) than the level of questions in this books. Of course, you need to focus more on Number Systems, Percentages and Geometry questions ( a little bit tough). I would recommend solving all the levels of this book as this would allow you to develop better concepts. Though all the questions are solved, I would recommend the following style of studying –
First understand the theory -> analyse how he has solved the questions in solved exercises -> next take up level 1 and try solving all questions -> if you are not able to solve a particular questions, give it one more try -> if you are still not able to do, mark it and go to next one and in this way try the whole section -> after you have tried all go back again to the question you were not able to solve and look at its solution ( given in the book) -> Go to level 2 and so on.
I think one book is enough ( of course there are millions flooding the market but if you try the above method of studying, one will be more than enough).
2. The DI and Logical Reasoning:
Many people blatantly ignore or fail to understand the capability DI has in improving their scores. In CAT, DI and LR are in both Quant and Verbal sections (Verbal one is bit difficult and is called Logical reasoning). Now suppose you are not that good in Verbal then you can still improve your score if you are good in reasoning.
Even in Quant section, DI questions are the easiest to solve and are marks guzzler. Many people attribute success in solving reasoning questions to luck or chance, but if you practice them hard during your preparation and maintain positive attitude on the test day, then you will observe your luck going in your favor.
I would recommend How to Prepare for Data Interpretation and Logical Reasoning for the CAT by Arun Sharma. I would recommend you to study 1 book only but make sure you study it completely ( see its better to study 1 book instead of 15-16 books thrown by your coaching centers, because in the end what matters is your understanding of the subject and not the number of questions solved)
Remember doing all the tests and practice sets given in the book (including the CAT actual papers given in the end). That will be more than enough.
3. Finally -The Verbal:
Yeah I know this is one section you have been waiting for desperately because anyhow Maths, DI get covered but it’s the Verbal part that zeroes all that effort. Even if you do not have a good background in English, I hope these books will be of great help. I studied them all ( that is why I only studied 1 book each for both Maths and DI).
1. For complete Verbal Review I would recommend – Conquering GMAT Verbal and Writing 2nd Editionby Doug Pierce published by Tata McGraw Hill. It is a must read for any serious aspirant.
2. Along with this for practicing Sentence Correction and Comprehension, I would recommend Kaplan GMAT Verbal Workbook. It’s a great book for preparation.
3. In CAT, there are some questions on close words (also called confusing words), you can try How to prepare for Verbal Ability and Reading. I wasn’t that much comfortable with this book in any other section.
4. Many students worry about Vocabulary. I would recommend practicing words provided by SAT or GRE on their website. They are very helpful. Though, Vocab is not directly asked but having knowledge of words helps. In fact, in CAT, they specifically add tough words at tough instances where the knowledge of the word completely changes the meaning of the sentence.
Well we have covered almost all the sections.
I would not recommend going into grammar books and learning all those rules. Instead, read the above ones they will help you better understand how to crack sentence correction and completion questions.
Remember books are a great help only if you study them the way they are meant to be. Spend a lot of time on them, of course you should attend parties and have fun but give the books their due share of time. Generally, in preparation books, authors themselves tell a great deal about how to study their books that is why I only named these books.
Also, try taking practice tests (mock tests) offered by coaching centers. They will be of immense help during your preparation.
I hope the above list helps. In case of any help, please feel free to comment in your queries.