I would suggest you to go through well with the previous year papers & Do practise as much you can, You can join the Test Series & attempt the test, It will also help you to analyze your preparation.

Here are some of the important tips for the preparation of NDA entrance exam you can follow given below:

Syllabus Details: You must have a proper source of the syllabus because a well-prescribed syllabus supports you in making a proper schedule for the examination.

Make A Proper Schedule: You should make a detailed schedule for the examination, those students follow a schedule they may get success in the examination.

Basic Logic Should Be Clear: You must do the analysis of complete syllabus as well as mark the important topics which need concentration.

Short Notes: Notes will help you in taking the permanent record, and it always helps to a candidate in preparing best for the examination.

For preparation of NDA you can refer to RS Aggarwal and Arihant Publication.

You can also refer to previous year papers to understand the exam pattern and level of the questions.

Good Luck!

Hiii

The written exam will consist of two papers – Mathematics and General Ability Test. The difficulty level of the questions asked in both the papers of the written exam will be similar to that of class 10 and 12.
So the correct study material is the most important thing you need. Here i am providing a link which has a list of best books for NDA.
https://competition.careers360.com/articles/best-books-prepare-for-nda

Along with these books you must refer to previous year papers and sample papers so as to improve you performance.

Thanks!