you will need to do a little leg work. Unless you have a highly sought after specialty, your rates need to be in line with the market, and the only way to find out is to get on the internet or the phone. Most trainers / studios have their rates on their websites, and that will give you some idea. Large gyms usually have set rates and will be very willing to share those with you as long as they believe that you are a potential customer.
I agree with Karin.
Call or consult with a few trainers that have similar levels of experience as you do, and find out what their rates are.
One fast way to do this is to use the IDEAfit directory for “find a trainer” and then punch in your zip code. Then you can find who trains near you, what they do, and what they charge.
Do a search from here on IDEA Fitness Connect of trainers in your zip code and surrounding areas. Then, you can take your own experience and get an idea of what to charge.
It will depend on a few factors such as experience, location, travel (in home or in a gym), the general market, and specialties that you have.