There is one keyword not to be forgotten in this all subject. The outcome of the process is, at the of the day, 'discretionary'.
Therefore, technically speaking, it can depend on the altimeter setting of the day in Dallas ...
Before going into the advanced rocket sciences certificates, or degrees, it might be appropriate to think of more mundane details.
Me109 mentioned that he was approved. His data mentiones him as being 44 years old. Would say that that's about the limit for a successful outcome. Younger than that is likely to be better. Older than that it might be a no go. Other stuff like being married with children might cause one to be regarded as a responsible candidate. Being single could be a deal breaker.