The most important piece of equipment that is necessary to make this art, is your finger nail. The index finger nail is by far the best thing to use to engrave away at the wax, and equally useful is a thumb nail to clear away greater swathes from the edges and larger areas of the picture, due to its broader nature. A rag is then used to clean off any wax still remaining.
The only real way to learn how to do it, is to just dive in and see what happens. The more engrossed you become into it, the more you will see, and what at first seems like an unordered mess will start to reveal all sorts of fantastic shapes, and stories will unfold with magical landscapes and enchanted journeys into the unknown. I love it. Each one is unique and has a special character that is almost alive.
It can be difficult to know when to stop, and there is often a conflict between wanting to keep some particularly nice part of morphed colours whilst also needing to remove it to improve the shape and lines of continuity. There is often the situation where more than one thing is asking to be revealed but can only be so by removing another one. Which one wins radically changes the dynamic of the picture.
When indecision paralyses you, it can help to squint the eyes to reduce your vision allowing you to see without too much information, which can then clarify the shapes and the path to take. I quite like to do it in the fading light after sunset.
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Below are a few examples of making art in reverse. These examples are certainly not the best that can achieved with the materials, and indeed there are an infinite number of patterns and shapes that could be deciphered and uncovered from the Starting Block of wax. But this will give you an idea of how it can be done and from there you can discover your own way and explore the worlds that will unfold as you look deeply within the inscrutable potentialities.
I have found that my index finger can become quite hot and uncomfortable while doing this, no doubt due to the concentrated usage of it (a build up of ch'i probably due to the intensity). But it is only lasting while doing it, and then only if being done for a long time, and afterwards it quickly fades and does not develop into anything else. Just thought I should mention it in case you experienced the same thing and became concerned. I call it magic finger syndrome! I've done over 500 of these, so perhaps it's my finger wearing out!