Many times people have asked for an opinion, and many times they have not. I have seen the results from both. As an instructor of over 30 plus years, let’s say more than I would like to admit to at this time in my life, I have come to many conclusions about this matter. The most important is to wait for someone to seek my advice before going with my heart and giving it.
Most importantly an instructor should be well trained, that doesn’t mean watching videos, or taking a few workshops. That means devoting their lives to the form of material they choose to become an expert at and anything related to the expression of said material and the dissection, history, influence and any other related information on their subject. They should also know and study how to express the sharing and processing of the information.
Another good indication would be someone that has studied under master instructors and or had a period as an apprentice. Partnering master instructors and aiding in classes is a good indicator. Years of accomplishments create the right mix of experimentation to know what works for each individual situation.
If a “teacher” has canned answers for questions, or says you will get it with practice, to most questions, chances are they haven’t developed the depth of experience to know the answers and are making up the answers instead of answering from learned knowledge.
Many make choices that are emotional. They are based on the looks, or abilities of their teachers on the surface, this is sometimes dangerous. Instead they should be based on the results of the students they have trained.
In the end, each person has different desires, and learning languages, that the instructors need to blend with. After finding out that you are going to a reputable, instructor, you still should have a good connection, and ability to understand and communicate together.