Lucent General English, Lucent General Science and General Knowledge are good resources to prepare for NDA examination, going through them thoroughly might give a cutoff clearing score. You must prepare for Mathematics very well, 12th level mathematics is sufficient, scoring good in Maths section will give a boost to your overall score. Also English of 10+2 is enough for NDA written test, main factor is to attempt GAT. You may also check out NDA Pathfinder