One of the responsibilities of a potential hypnotherapy client is to do everything you can to make sure you are working with a highly trained professional. Do your homework. Ask for referrals from your medical doctor, therapist or counselor. Ask friends whose judgment you trust if they have used a hypnothrapist they could recommend.
If you have not been able to find a trusted referral, phonebooks and the internet are just a place to start. Call a number of professionals in your area. Many hypnotherapists work in one person offices, so you will probably be dealing with voice mail or an answering machine. Leave your number and ask for a call back. Professionals return calls.
I do not think it is inappropriate to ask for a free consultation either over the phone or in person. I offer a free half-hour consultation in my office to every new client. The advantage of taking the time to go to the office is to actually meet the person with whom you will be working and to see what kind of surroundings you will be in. If you feel uncomfortable being in someone's home, you may be more comfortable in a professional office setting. The interview itself does two things, it gives the potential client a chance to meet the hypnothrapist and make sure they feel comfortable. It also gives that person a chance to ask any questions they might have about hypnotherapy so they understand how it work and how it could be of value to them. My grandfather used to say , "You don't want to buy a pig in a poke." You need to get your questions answered so you understand what you are buying when you hire a professional hypnothrapist.
Like any other purchase you make, you want to make an educated decision about your choice of hypnotherapist. Do your homework so you will have a great hypnotherapy experience.