I attended a class by a Sports' Psychologist at the University. And he very gently introduced the class to the experience of trance. He pointed out the traps and gave us suggestions for safety.
Also I bought books by Dennis Weir.
And I joined the site of Dennis Weir called, The Trance Institute
But sometimes I just listen to binaural delta waves and watch the fractals unfold on kL3z, but you need stereo headphones for it to work.
Trance is a normal part of daily life. For instance you enter the hypnogogic trance just before you fall asleep and just after you wake up.
And you enter and leave trances all during the day. And we take this for granted and it is normal.
So essentially you are learning to become conscious of something you do normally all during the day.
If I wanted to be pretentious - and I do - I would say, it is making the unconscious, conscious.
And you know you are on the right track, when you feel relaxed and refreshed after a trance experience - when you are fully awake.