When observing private education at ordinary times, we should first find out which coaches don't work and which coaches don't have clients at all during these periods. If these two situations are generally not considered.
Secondly, the intensity of the coach's training with the students. If you often go to the gym, every time you see a coach training with someone, you can choose him, because he is undoubtedly the most popular in this gym.
Also, it depends on whether the coach is serious. Generally, a serious coach will always pay attention to the actors' movements and correct them as soon as he sees something wrong. Such a coach deserves to be the first choice.
Finally, it definitely depends on the professional ability of the coach. You can consult other members, or ask him one or two questions you are puzzled about, and judge his professional ability from his answers.
As long as you do this, the private education you choose should not be wrong.