Scrying is the art of seeing and interpreting visual pictures or patterns that can seem to appear when gazing upon a suitable surface or background. In effect, you are projecting your visual imagination onto an object.
Ideally, you want to use an object that does not provide a point onto which to focus. The idea is that by not being able to focus clearly on the object, you can stimulate the minds ability to form pictures much as it does when you are dreaming. But, since scrying occurs while you are conscious, it is more properly akin to a hallucination.
The most well-known of these types of objects is of course, the crystal ball. Another is the so-called “black mirror” which consists of a bowl that is painted on the inside with a black matte paint. You could also use something as simple as the screen of a cellphone that is turned off or even a glass full of water. Another option is to make a pair of Ganzfeld goggles by cutting a ping-pong ball in half and securing the two hemispheres over your eyes so that all you can see is a glowing white field. You can even just close your eyes and look into the darkness behind them. In the days before digital screens, many people would tune a television to a non-receiving channel and just stare into the static field.
The idea is to rest your gaze upon the chosen surface gently without trying to see anything in particular. Then keep in mind what it is that you want to know about. Eventually, your mind will begin to form pictures that appear to be located on the surface you are looking at. They are similar to the hallucinations that arise when you float in a sensory-deprivation chamber.
Some people will use a different sort of scrying by looking for recognizable patterns on a random surface similarly to seeing shapes in cloud formations. Tea-leaf reading is an example of this.
In scrying, as with other types of divination, the key ingredient or tool is the mind itself and it’s links to the depths of the underworld. You consciousness is a part of God’s Consciousness that Consciousness can see everything.