Well, it is not that easy to get hypnotized. there are a few "rules".
1. You can only get hypnotized if you realy want to, and I do not mean "Oh I want to get hypnotized" I mean your subconcious min has to want to experience the intended effects. It will not work if you have any doubt.
2. You have to trust the hypnotist (or hypno file) so if it helps you listen the file before you start a session, so that you know exactely that the file is save and does only what you want it to do.
3. Try to turn down any things that could interupt you. Switch lights off, make your room silent, try to focus only on the file, in the words and do not let other things distrect you.
And remember hypnosis is not magic, it will not work after one session.
I hope this will help you a bit.