Choosing the right golf coach is a really big decision. If I were doing it I would begin my search with finding a coach who continues his/her education with certifications. Being a “good player” has little or nothing to do with it. Finding a coach who is certified in plane truth, stack and tilt, A swing, some form of continuing education. They need to be simple not complicated. Most coaches are far too technical because they want to impress you with how “smart” they are. Most of my clients are far “smarter” than me. In my opinion the most important traits of an elite instructor is they put their hands on you! As humans we learn visually, verbally and kinesthetically. An elite coach uses all 3 of these in your lesson and illuminates the path from where you are now to where you want to go.
I also recommend finding a coach who has worked under or with elite instructors. I hope that helps and remember the advice you get is generally worth what you paid for it!