Hi Jessica! Definitely start with researching what local trainers are charging, but more importantly consider what your time is worth. Yes, having lower rates will get you more clients but if you know your worth and own it you will gain more lifelong clients. People who are serious about this will know and respect what your time is worth and what their goals are worth. The average for trainers in my area is $30 per hour. I charge $45 per hour and have a much more loyal client base who are dedicated to their training program because they know that this is an investment rather than a financial loss.
I have seen anywhere between $30/hr. and $100/hr. Like everyone has said, it depends somewhat on your market, but also on who your ideal client is and what they will be able/willing to pay for the value you are creating for them. I basically charge $45/hr for gym clients and $55/hr for in-home and offer packages with slight discounts.