I consider that there are two forms of divination - pattern forming, and random indexing. Random indexing would be stuff like tarot, runes, etc - where you pull cards, stones, or other such objects and interpret the meanings of them. Pattern forming would be scrying of all sorts, such as tea leaf reading, casting the bones/sticks/stones/shells and examining the patterns that they form. In using these methods, we are observing the patterns they form, thereby finding meaning in chaos.
The most popularly-known method of scrying is, of course, the crystal ball. One gazes into a clear, flawless crystal and lets the mind blank. Eventually, images start to form in the crystal, and the Witch interprets those images to divine an answer to her question.
I was reading recently about ganzfeld hallucinations, and thinking, "Wow. That's exactly like what we do when we scry." There is a lot of scientific evidence that when the mind is deprived of input, it starts to form its own. Similar things have been reported by people who spend time in sensory deprivation tanks.
The procedure for creating a ganzfield hallucination is simple - cut a ping pong ball in half and tape it over your eyes. Turn on the radio and tune it to static. Lay back and watch, listen, and enjoy. Don't stand up too quickly when you return to earth.
The mind is so active, and it needs to find meaningful input, even when there isn't any that is readily apparent. As Witches, we learn to not just enjoy those patterns, but we learn to seek out in those patterns the answers to our questions, because in looking into the deeper parts of the mind in this way, we are able to access deeper levels of understanding not always readily available to us in our busy, cluttered, distracted and noisy minds.
Many ceremonial magicians use scrying in spirit conjurings. They put a black magic mirror into a "triangle of the art," (a triangle with names of power, magic words and symbols on it) and through their rites, they summon a spirit which they can see and communicate with by looking at it in the mirror. The triangle fences the spirit in, so it can't go running amok and causing havoc.
Magic mirrors and crystal balls may be common, but one can scry into anything that has random patterns. Since we are going to be going out into nature for Midsummer, and since Midsummer is typically a time when the world of spirits is active, we're going to try scrying into more natural things - running water, tree bark, a bonfire, clouds, shapes in stones and plants, and so on. Spirits of nature would most likely be seen most readily in things we find in nature. Dryads are spirits of trees - so look at trees to see them. Undines are spirits of water, so look into the water to see them.
Did you, as a kid, ever lay outside and look at the clouds and find rabbits, birds, and dragons in them? I did - I would gaze up at the clouds for what seemed like countless lazy hours and observe the shapes they formed. Little did I know, I was doing a form of scrying. If you haven't done this in a while, try it out - scrying is easy, but it does take practice to get good at it. The more you do it, the more you'll be able to catch glimpses of the spirit life all around you.
Also, bear in mind, scrying does not just happen with the eyes. You can scry with sound, touch, possibly even smell and taste. Though I've not personally had much success with these, I have heard people say, "Something smells bad here, let's leave," when they get a bad feeling about a situation. Perhaps they really are smelling something bad in the air?
Try listening to the random noise in nature, in the city, or anywhere in the world around you. See if you can hear anything in those patterns. If you want to get really experimental, play around with the idea with scrying by touch and smell.
Here are a few links on some other methods of scrying, with some exercises to help you better your abilities with scrying.
Also, if you are interested in learning more about the ceremonial magicians, and their use of the magic mirror, take a look at these wonderful videos by Carrol "Poke" Runyon, who is the founder of the Temple of Astarte in California. (http://www.templeofastarte.com/) He's very informative, and the videos give a lot of his own insights into the spirit world, spirits he has worked with, and how some magicians conjure, communicate, and work with spirits.