Actually, scrying can be done by looking at anything, even into the distance, which would take a bit of work to do correctly. But yes, scrying is usually done from a bowl of water, crystal balls, fire, smoke, etc.
I have done scrying and it's an amazing experience at first, as you never know what you'll see. If you're interested in a specific scrying method, let me know and maybe I can help you figure it out. :)
My personal way of scrying is over black coffee in a lead crystal bowl, with a quartz crystal at the bottom. I've tried many other liquids as surfaces, but I feel that coffee, with the magickal correspondence to the mind itself, gives me a better medium. The quartz at the bottom charges the coffee with the receptive energy I desire. I only need to sit there for ten minutes tops before the messages start to flow freely.
I've tried quartz crystal balls, I didn't like it. Perhaps it was the particular crystal ball I used and the numen(inhabiting spirit) within, but it just seemed more of a struggle to use than other ways I've tried. If I come across another one that draws me, perhaps I'll try again. I'm thinking of using a different gemstone/crystal that can be seen into, like fluorite.
I used a labradorite slate under candle light which was very effective. There was a particular pattern on it that would actually change and looked as if it formed shapes/pictures once I entered that perfect mental state. It was very interesting because I would look for the images afterward on the stone and couldn't find them again for the life of me! Ah, the power of the subconscious! Lol But unfortunately the stone was lost in a move to another house.
But my favorite is scrying fire. It comes naturally to me. No true way to describe it, I just mentally become immersed into the flame(s).
Well once you find your medium, get into a light trance state and stare into that medium, but with a gaze as if to make your vision a bit blurry. Let whatever you see to come freely. Let's say you want to scry with water. Just fill a bowl up, and start the method I just explained. Soon you might start seeing messages or pictures in the water or your mind. This is what scrying is, using that medium to capture a message of some sort. Note that this is how I personally scry and it might be different from others. If I was unclear on this, mail me.
With water, I would use a dark bowl and add some black ink to the water. When you scry, you are blending your energy with the energy of the medium, so, images are within the combination of those energies, as much as seeing images in the medium alone :)
