Are you a director of a team of personal trainers?
I have been, in a number of different venues. First qualification, obviously, is education and training, along with certification and continuing education from a challenging, recognized authority. Training trainers is an exciting and fulfilling opportunity. Harris’s thoughts are right on the mark. In my mind the most important consideration is finding those whose most important focus is the safety and training response to the clients with whom he/she will work. Always focus on the fact that the workout is for the client, not the trainer.
Good luck.