I am an undergraduate student pursuing Engineering. I need help with how can I prepare for GMAT and CAT and what is the criteria for admissions abroad?

Hi Ronak,
I am a pass out of IIT Kharagpur 2015 batch.
There several institutes which provide coaching for CAT exams, among them I have referred the materials from career launcher and times institute for preparing for Aptitude exams during placements.
 Their materials are right; you may join any of these two institutes.
You may also try for correspondence from the institute mentioned above.

If you’re applying for a graduate-level degree, especially a master’s program, you may be required to submit scores from one or more standardized graduate admissions tests. These are internationally delivered tests which aim to ensure applicants are prepared for the rigors of advanced study, in their own country or abroad.

CAT and GMAT both exams are tough, so you have to prepare well to score well. Arun Sharma books for CAT will help you. Reasoning section in CAT is the toughest so practice that section well, give mock tests online I would not recommend joining coaching better study online courses. Now the second part is GMAT; your CAT preparation will help you in GMAT also. The level of GMAT will be higher than the CAT, so prepare well. In abroad they want good GMAT score with work experience.

You can give an exam like GMAT and MAT in the final year of engineering.
Firstly, you start by learning the basics of Mathematics. After that, you have to practice from the lower level to a higher level. Same as reasoning.
An essential part of this exam is English, so you can proceed with basic, practices and read the newspaper daily and also by doing exercises of spoken English.