My way in....
1. Engineering degree
2. I applied for a job with a large multi-national defence manufacturer
3. I was given a job in the flight test department
4. I slowly learned enough to think about calling myself a flight test engineer.
Not too complicated really!
My advice for what it's worth....
Try and get a job in a large and established flight test department. These organsiations are the ones who can afford to spend money on training.
Try not to bullsh1t too much.
Integrity and the respect of your peers are important in a small specialism. If you BS, you have neither.