There will be postings in various Departments like FCI, ESI etc where there would be openings in various Government Sectors. You need to apply for the same. And if any position falls vacant in any Government Hospital, the HOD of that Department or Hospital also gives an advertisement for filling the vacant position. The same goes with the positions of Assistant Professors and Professors as well. You need to apply as and when the openings are there. And you can also appear for UPSC or State level Service Commission exams for opportunities. And then you can also write SSC for working as a Doctor in Army, Military or Navy.