Government & Defence Entrance Exam

That's a pretty good question. If you have decided your goal, you shouldn't go for some technical courses like engineering. Go for some courses which don't require much effort like B.Sc, BA etc. BA is something which is preferred by most of the aspirants since it gives an edge over one subject while you are preparing for civil service examination. My suggestion is to go for BA in history, civics or economics, because all these subject play an important role in civil service examination.

There are a couple of links. Click and download the documents to prepare- http://recruitmentresult.com/nda-preparation-books/
Guide for NDA/NA examination
Topic-wise solved papers of last 10-11 years
Guide to quantitative aptitude
NDA books pdf free, download of Compendium, General Knowledge
And, many more PDFs.

As you are preparing for UPSC, you can try for IAS or even IPS.

The students who aspire to become District Collector are required to write the Civil Services examination that is carried out by the Union Public Service Commission. The exam has three parts. They are: Preliminary exam, Main exam and Interview. The advertisement for this exam will be proclaimed in all leading employment newspapers. They will also be displayed in the authorized website of the respective State PSC.

Get all details of NDA through this link : https://www.shiksha.com/exams/nda

Well, you have to focus on both equally, as if you don't qualify both, you will not be selected. So, it is very simple and crisp.

The last date to submit the application form for NDA (1) was February 04, 2019 and NDA (2) is September 03, 2019.