I did a forum search in this forum and, although there is quite a bit about scrying in general, I didn't see a whole lot about crystal balls specifically. If I managed to miss a thread, I apologize in advance!
I have had a lot of upheaval in my schedule and life in general and have not had time to practice my workings as much as I had wanted to, so I decided to throw myself 100% into divination, since that's a practice I tend to have a natural knack with. Cards have been my usual method, I started fortune telling as a (Christian) teenager and moved into tarot in my mid 20s. I've tried scrying in a normal mirror without much success, so dropping an enormous chunk of change was not something I was willing to do for scrying, although I've been attracted to the idea of crystal scrying for a long time. Yesterday I met a selection of selenite balls for around $20 and figured if nothing else, I'd have a pretty gazing ball for decoration. Of course I bought one. I attached a flash on and a flash off picture, although neither really do it justice on my cell camera.
Now, I used to have no problems at all with visualization, but over the last year it's become a struggle. Last night I inducted the selenite into my collection and gave it a go and much to my astonishment, I had wild success. After struggling to visualize at all, I saw a rich selection of images that made perfect sense. The point of my session last night was just a sort of "get to know you" and it was more than willing to speak.
I don't know anyone else who uses a crystal ball, but if anyone here does, I'd like to hear about your experiences and techniques.