NIFT

Well, you have to give good amount of time for NIFT preparation. Revise all basic Maths formulae, and practice questions, which will help you solve many class 10th level Maths questions. Be updated with current GK, not only national level, but with international events as well. Good vocabulary will score you much more. I would suggest, English is the main part of the paper that helps in scoring the most, so improve English grammar and vocabulary. You should have the basic knowledge related to history, geography, economics, and general Science up till class 10th. Go for aptitude books. Apart from this, you can download sample question papers online related to the drawing part, I. e, the CAT. It does't matter if you are not very good at drawing, what matters is your idea and concept you put into your sketch. You're given marks on how far you can think out of box. So practise this as well. And you still find difficult to decide how and what to prepare, go for any design coaching. All the best.

Hello Ananya,
Here's a little preview:
NID is an Indian institute for product concept development and design innovation. NID teaches students about design and art, aesthetic sense and extracts of design engineering. Focused on art, aesthetics and product development. NIFT is leading institute for fashion design and year-on-year the best stylist and fashion designers have emerged from here. NIFT is focused on fabrics, illustration, aesthetics sense, garment construction, styling, etc. The focus is more on apparel and clothing. NIFT is mostly dedicated to fashion world like leather, textiles, lifestyle, knitwear and fashion and communication. It was set up in 1986 in the collaboration with the objective to deliver high-quality training to aspirants in aesthetics and technology of fashion and textiles. NIFT currently provides a four year Bachelor's degree programme, a two-year Master's degree course and Ph.D programmes. With OPUS training, you will be prepared to crack the entrance exams to these institutes. While OPUS mainly prepared for NIFT, the training will help you get into other fashion and design institutes.
Rest is your choice, be wise.