CBSE 12th

Firstly, you need to keep an eye on the application dates. Make sure you apply on time. Read up on the admission process and start preparing accordingly. https://www.nift.ac.in/sites/default/files/2017-11/Guidelines.pdf
Here are a few tips for that-
Hi, There are two part to the first level entrance test- Creative Ability Test CAT and General Ability Test (GAT). CAT is the most important part of the question paper. Start sketching and develop your own style of sketching and coloring. I can not stress this enough. Good drawing skills are very important. How you present/draw your ideas is just as important as the idea itself. Keep reading the newspaper (especially around November-December) It'll help you in GK part of GAT and help you generate better ideas. Most questions in CAT are related to current scenarios. For example- Make in India was started in late 2014 and in the 2015 entrances Hi had asked the students to make a mascot and a poster to promote the same. Based on the happenings and big stories in the media, plan and create small sketches. This was you'll save time on thinking during the actual exams. Go through various artists on social medias, movies, art galleries etc. To find inspiration. Go through question papers from the previous years and see what kind of questions they ask. Start solving these question papers in the given time and work on pacing yourself. For that, you can pick up any reference book. Math, logic and English are mostly what you've learned in school but it's better to revise. Keep solving the previous question papers so you can get into the habit of thinking along those lines. You can pick up any test series or books from Arihant publication. They usually have a summary of the portion. Check out other artist's work on Instagram, Interest, Behance, etc. So that you can improve your drawing skill and understand what the rest of the world is doing.

Ho Jainil,
It depends on what type of job you want to pursue. To earn money you need to excel in that field. I know people who completed their degrees from mediocre colleges but had great professional skills and today earn more than those from premier colleges and lacked those skills. Other kids who were rebellious enough to pursue their dreams and had enough diligence to excel in their fields also make a lot of money. I cannot tell you what course you should pursue but I can definitely tell you- find your calling. Colleges can give you degrees but cannot instill professional values, communication skills, and art of influencing people or leadership. That you will need to master all by yourself. Read more books and give all to your work. When you will love the work you are doing money and success are the byproducts, satisfaction is more important.