As you have asked about the tips to clear Common Admission Test (CAT) exam, I am giving you information about it, check below for the details
Firstly you should know about the exam pattern
CAT 2015 pattern was
There are total 3 sections in the exam namely:

Verbal and Reading comprehension
Quantitative Aptitude (QA)
DI (Data interpretation) and logical reasoning

No. of Questions per section:
Section Number of questions
Quantitative aptitude (QA) 34
Data interpretation and logical reasoning (DILR) 32
Verbal and reading comprehension (VRC) 34
Total 100

Now CAT generally checks the logical and analytical ability and questions are of some higher level.
So you should clear your concepts about every topic.
You should have a good practice for each section.
Make a proper time table to study.
Try to solve previous year papers or you can join some test series.