To clear CDS, you must earn at least 20 marks in all subjects, which is the sectional cutoff, and 115 points in all three papers combined, which are English, General Knowledge/Studies/Awareness, and Maths. Of course, if you want to join the Air Force, you should aim for a score of roughly 145/300. However, for Army and Navy, a score of 115/300 should sufficient, though the higher the number, the better.

English - Solve all Previous years papers of CDS

GK - Lucent’s or Arihant's General Knowledge and Study Capsules for Polity and Geography should do the trick if you’re lazy, otherwise I’d recommend NCERT (Classes 9–12) + Indian Polity by M Laxmikanth also The Hindu Newspaper for Current Affairs and Editorials.

Mathematics: Quantitative Aptitude by R S Aggarwal and M Tyra for high speed shortcuts will work best.

For TGS you just have to prepare for ssb.

Afcat- exam is more static Knowledge based.

Maths (18 ques): basic 10th level Maths is asked

Gk: static gk based on current affairs

English : solve previous year papers

Reasoning : You can solve any book for reasoning as practice is the key here.