Hello,


First of all try to get very good grades/marks in your 12th board.Try to get 90+ marks in Physics and Mathematics. Then after completing 12th you should have IELTS or TOEFL score of minimum 6.0.
When it comes to which country then Russia is considered to be the best country for studying masters or graduation in Aeronautics and Aerospace Engineering and then ofcourse USA is also one of the best for admissions.

I hope this helps.