Mass Communication & Media Preparation

First, you should get your hands on previous year's papers of the college entrance exams. Try and answer them. It will give you an idea as to what line of questioning the exam takes.
In general, Mass Communication and Journalism entrance exams test English Grammar, Writing Skills, and Knowledge of Current Affairs and Critical Writing ability. Critical writing is not criticizing, but being able to grasp and break down a problem to explain it then offer probable solutions or answers.
Reading newspapers, knowing the media landscape, watching news television and trying to understand why Arnab Goswami shouts so much, why newspapers write in a certain way and why news on internet portals is so different are some of the things that you may need to know and answer. There will be questions on Media Policy, Laws, Ethics, Films, Books, controversies, free speech, election propaganda, news coverage and so many other things.
After getting through the entrance test there will be a personal interview, which will test whether you have the content to back up your statement of purpose from the test. Basically, you need to know everything under the sun. Sounds intimidating and it is but it is not impossible.