earn (one's) stripes
To prove that one is deserving of a particular position or designation. I told the recruiter that I earned my stripes as a teacher before moving into administration.
earn one's stripes
Gain a position through hard work and accumulated experience. For example, She'd earned her stripes by serving for years as the governor's secretary and personal aide . This expression alludes to a military promotion or award, indicated by strips of chevron or braid added to the recipient's uniform and known as stripes since the early 1800s.