How lucky your students were to have had you helping them with guided imagery for test anxiety! Lots of teachers wind up learning it for just that reason, and often intuit their way into doing some pretty spectacular work, with or without the training.
But there are hard skills to be learned here too, and plenty of places to get them. For starters, I strongly recommend you join Imagery International, a classy, practitioner-focused professional association of guided imagery clinicians. They serve as a networking and resource center, put out a terrific blog, print a first-rate journal, host teleconferences featuring experts and hold an annual conference filled with equal measures of content and warmth, expertise and inspiration.
There are books, too. As a retired teacher, you’ll be interested to know about Janice McDermott and Joan Stewart’s Grand Ideas from Within, a program for middle schoolers using guided imagery, and it has a companion guide that clues you in to how they go about it.
Another important kids’ imagery resource is Charlotte Reznick’s excellent new book, The Power of Your Child’s Imagination.
For working with adults, there’s Andrew Schwartz’s Guided Imagery for Groups – a wonderful collection of imagery scripts, ideas, and pointers for using guided imagery with all sorts of groups.
Marty Rossman, the pioneering co-founder of the Academy for Guided Imagery, has a new, revised edition of his classic book, Guided Imagery for Self-Healing.
Julie Lusk wrote the very handy 30 Scripts for Relaxation, Imagery & Inner Healing – Volumes 1 and 2 – with many pointers and suggestions as well as scripts from a variety of practitioners and styles.
My book, Staying Well with Guided Imagery offers scripts, advice on construction of a narrative and research to back up some claims; I actually put a lot more practitioner advice in Invisible Heroes: Survivors of Trauma and How They Heal.
If you want a training program, The Academy for Guided Imagery hosts an excellent distance learning program; The Bonny Method of Guided Imagery and Music (GIM) uses a different but just as excellent approach, more featuring the music with the imagery spontaneously growing out of the experience of listening, but there doesn’t seem to be any central training organization any more – at least not that I could find. Rather it seems to have gotten dispersed among several Bonny-trained practitioners, and I just don’t know them to vouch for their particular classes one way or the other - just the method, which is beautiful and powerful. Susan Ezra and Terry Reed’s Beyond Ordinary Nursing may still be doing their superb training, too. Seems to me they’ve slowed down some, as well. (They are both very involved in Imagery International now). And there’s a Center for Healing and Imagery in the Washington DC Metro area that has a terrific curriculum of weekend workshops and they teach both Interactive Imagery and Somatic Imagery.
I hope this helps. Best of luck with this!