There are many coaching institutes available in India so it would be better if you can share which particular state you are aiming for.

Also, you can consider few names -

Aakash Institute South Extension-II

The Cavalier C-73, Sharada Puri, Marble Mkt

Ground Zero Institute 9

Disha Academy etc.

Hope

The minimum qualification should be 12th pass as you cannot join Airforce, Army and Navy after 10th. So I would suggest you to focus on your 12th first and once you clear it with decent score then try for the same.
Here is the eligibility for NDA - Age limit

If you are prepare for class 12th you can easily crack NDA exam. In order to crack for NDA exam you can make a plan. So, you can cover the important topics and you get time for revision. You should solve mock test series daily to analyze your preparation level.

There are 3 sections of the Armed Forces- Army, Navy and Air Force.

You have to appear for NDA exam in order to get into.

Below is the eligibility criteria of the exam you can check

Age Limits:

• Minimum Age: 16.5 years

• Maximum Age: 19.5 years

You can also check

CISF stands for Central Industrial Security Force. The security at Delhi Metro, Airport etc is done by persons serving under CISF. 

The best way or opportunity to join CISF is through the Central Armed Police Force Examination conducted by Union Public Service Commission every year.

Below is the eligibility criteria

The Central Industrial Security Force is a Central Armed Police Force in India.
Industrial sectors like atomic power plants, space installations, mints, oil fields and refineries, major ports, heavy engineering, steel plants, barrages, fertilliser units, airports and hydroelectric/thermal power plants owned and controlled by Central Public Sector Undertakings (PSUs), and

I am sharing a link which states complete syllabus for NDA entrance exam.

Exam Pattern: Overview of paper pattern Exam mode –

Number of papers – Candidates appearing NDA paper will have to answer questions from two papers– Mathematics and General Ability Test.

Exam duration – The candidates can