I got into NID ten years ago, and am still in awe of the place and the wonderful people I met while I was there. I have always felt a little doubtful about how/why I made it through the admission process. But here is what I know and sharing it with you, hoping that it helps.
1. You don’t have to be good at drawing to get in. They will teach you all the skills needed to become a good designer. BUT you have to be a suitable candidate to receive their teachings. Being well-informed about current affairs, reading books outside of your school curriculum and being a full-time observer would help you (in life! not just the NID entrance exam). You have to express yourself well, through creations, words, doodles and interactions.
2. The exam is different than the traditional entrance exams. Based largely on Carl Jung’s psychometric evaluation principles (the ones used in the evaluation for officer level entry candidates in the Indian Army – Service Selection Board interview). That means you cannot prepare for the test the same way you prepare for engineering entrance exams. You have to be prepared for situations and not specific questions. To sum up, if your aptitude lies in the field of creativity, you would fare well no matter what the questions are.
You will be taken through different kinds of interesting tests and there are no right or wrong answers for those questions.
2.1 You will hear about “NID Entrance Coaching” in your city. I have mixed views about joining one. It might help you by facilitating interactions with like-minded people and by getting to practice your social skills and overcoming stage-fright. Remember, you will meet the best and quirkiest minds when you go for your test and you shouldn’t feel diffident about your chances by meeting them.
3. As Pooja answered, be observant. Be open. Draw parallels from different walks of life. Don’t be restricted to what you know now; read more, learn more.
These are most of the points I can share based on my own observations and experiences. I was preparing for the Army but I didn’t get through. Although a lot of what I prepared, came handy during the NID entrance. I wish you luck for the test.
Word of advice: NID has an impressive collection of book, journals, diploma documents and movies. When you get in, DO make use of your library card. Most of the alumni I know (including myself) regret not doing so. I used to sit there only to escape Ahmedabad heat.