Sometimes you will discover that an induction may not work and more than that, the client may not tell you that it is not working and pretend to be in trance. The client leaves your office thinking you are a bad hypnotherapist, and more than that, that they can't be hypnotised. 
What hypnotherapists most want to do, is to create change within the client. To work towards a positive outcome. 
Many people have a misconception about hypnosis, especially new Hypnotherapists. Sometimes you may try several induction's and still find the person not entering trance and this at first can be most frustrating, as you, the therapist may think "oh God, what do I do now" The more you fail at inducing trance the less likelihood of them in believing that you are a competent hypnotherapist and consequently, your suggestions are measurably weakened as you appear to possibly stumble and find other ways to hypnotise. 

Usually, you have an hour or so to work with the client. Some of the mistakes that new Hypnotherapists make are to: 

• Rush into an induction… first, always build rapport. What does rapport mean? : Affinity, agreement, understanding, harmony, empathy, compatibility, partiality, unity. Take your time with the client, listen and set the ground rules of hypnosis (what it can or can't do).
• Fail to observe. You must observe the client. Some that know the techniques of N.L.P. can build rapport by matching breathing, pacing and leading (for those unfamiliar with these terms, a good NLP book will explain).  Read the clients body language, around 70% of all communication is non verbal. Notice their breathing, if they sigh when talking about an issue. If their communication is contradictory to body language. Notice and observe.
• Fail to test the hypnotic induction. You know what hypnosis is, and maybe what a hypnotised person looks like. But the client does not. Once you are satisfied that the client is hypnotised, test it. ALWAYS test it. You're not proving to yourself that they are hypnotised, you are proving it to them. A good test is : "Your eyes are so relaxed you can't open them, when I say open, they will remain shut” ---“if you open them, I will just click my fingers, and you will close your eyes and relax deeper”.
• Failure to deepen the trance. Use everything to deepen. Take the above command. “Your eyes are so relaxed you can't open them, when I say open, they will remain shut” ---“if you open them, I will just click my fingers, and you will close your eyes”:  then add, “and as you close your eyes, you will triple your level of trance, going deeper and deeper. “Notice that I use the word “Trance”, Trance is specific, relaxation is not hypnosis, if you say “and you will go deeper and deeper into hypnosis, or the hypnotic state”  you lose them as they do NOT know what that is or feels like.
• Failure to utilise. When taking a case history and listening to the clients problems, jot down the words and phraseology they use. You can utilise them in subsequent suggestions. This creates a bio-feedback loop to them, and easily targets the problem. An example: say the client said (in history taking)  “well he went bananas and trashed the place”.  If you said to her in trance, “Notice your boyfriend wrecking the place as he went berserk’ it does not fully connect with how they have mentally stored the experience or memory. If, however you said ” as you notice that when we went bananas and trashed the place” it more specifically targets. If the person's  phraseology for “warm and good” is the word “special”  then say “you can now feel “special “ and as you do so you feel warm and good on every level.
• Failure to utilise Non Specifics / Specifics. When you want information from them, ask specifically. When you give therapy commands, use non specifics example: How specifically did it affect you?” When giving therapy, not always but when necessary, non specific suggestions such as. “ now make all the changes within yourself  that you know you need to make to create the healing that you need"
• Failure to be professional. A trend I have noticed lately is how new hypnotherapists 'de-value' what they do. They say to the client “all hypnosis is self hypnosis, I am only your guide, you do it all”. Well, the client might then think  “what the bloody hell am I seeing you for then?” They don't want a guide, they want a professional. Now you can't do it for them but you can build “expectation power “ and you lead them to the results that they want. Sometimes, you have to avoid the word “Suggestion” and replace it with the word "command"  If I suggested that you wear a blue outfit on Thursday, it does not mean that you will.  But if I said “As you hear my voice, obeying my positive healing commands at all times” You find that you have a willingness and motivation to dress well”  it has more power to help create the change needed.
• Failure to use post hypnotics. Post hypnotic commands are necessary when you work with a client.  A simple post hypnotic, "And each and every time you are in my presence, you will instantly and automatically feel safe and secure. The moment you sit in the chair and I direct the words “deep asleep” to you; your eyes will close over lightly and you will drift to an even deeper state of trance than you are now in.”