Look at the job you want and work towards it. See what others in that position have done, and reach out to them! people are always willing to help and give advice on how to get jobs. BTW most astronauts start of as being an engineer or pilot, as they have most of the skills needed. Read up on some of the famous astronauts biographies, they might have some good tidbits. I personally love a book called “the right stuff”, and is all about the first astronauts.