Psychic or clairvoyant ability in a tarot reading is directly related to one’s ability to work with one’s Holy Guardian Angel. This is true for anyone who is working on their spiritual development, so in the early days the going can be tough. (There are people with natural psychic and clairvoyant talent, but they are not necessarily doing anything to improve – why should they when tarot is only about predictions?)
When Rose Kelley told Aleister Crowley to expect an important transmission on their honeymoon in Cairo, he was not expecting his Holy Guardian Angel to appear, so when later he wrote rituals for your HGA, he never needed them. Be suspicious of anyone who claims to have successfully completed the Abramelin Ritual.
The Book of Thoth in conjunction with the Opening of the Key tarot spread was expressly designed by Crowley to develop the ability to work with one’s Holy Guardian Angel. Simply by conscientiously working with the system, and reading for clients you develop your communications.
Clairvoyant explanations
There are all kinds of explanations of how clairvoyance or whatever mechanism you wish to describe the ability to make predictions, including weird and wonderful contortions using the sephiroth on the Kabbalistic Tree of Life.
Tarot teachers wedded to the Rider-Waite deck go on about looking at the pictures and symbols on the cards, which is equivalent to children looking at pictures of letters of the alphabet as they learn to read. As children get older, it is no longer necessary, unless of course you are a tarot student.
HGA Clairvoyance
For me, clairvoyance means the images that appear in my mind’s eye against a black background, that have relevance to the purpose or situation, and these images change as energy is applied. The clarity or otherwise of these image are related to the perceptual bias of the client, who often believes he has no psychic ability.
Where do those images come from? Quite simply, they originate from your Holy Guardian Angel who is communicating with the HGA of the client. I am sure you can see the problems, for if you are only able to have a small percentage of your ability to work with your HGA, and the client has even less knowledge, then perceptions will be cloudy, or problems with mis-communication on either side.
However, when you are working with your Holy Guardian Angel, your tarot readings will be transformed from the mundane to powerful healing sessions.