You ask for their resume. You ask questions. You do your research. Some simple questions to ask
How much Continuing Education do they do each year? Are they continuing to grow or do they stay inside 4 walls training themselves and their clients 12 months a year?
Do they do Assessments and Re- Assessments? Do they customize the workout based on you or do they train you on their favorite program or current fad? Do they re assess on a regular basis to see if your program is producing the results you want?
Ask them what there Strengths and Weaknesses. Good coaches know where their passions lie. They build a good team around them to compliment their weaknesses. They refer clients out to specialist on their team so that the client can get comprehensive attention.
These questions are a good jump off point. Finding someone calling themselves a trainer is easy as finding someone calling themselves an actor in Hollywood. Make sure your find a good one. It’s your body, health and money make sure you choose wisely.