This is a very interesting question, that may have a thread of other questions leading out from it? As an example ... Well aren't I the one who is supposed to get inspiration in my own life, don't I know what I need to do? Is this something God warned about in the New Testament? Do you practice magic or something like that if you use cards?
First off ... people get readings because there is an obscure area of life, and they are up against a block, and they have their suspicions, but their own impressions are not confirmed. I have noticed this is the main reason people become interested in more clarity...literally a clearer vision.
An individuals' vision can be blocked for many reasons, like strong emotions less neutrality, non-acceptance of inner promptings, self-will, and distraction of the world situations around a person. These are actually many of the things that meditation teaches us, coupled with prayer...it really does come down to "be still and know that I am", found several times in scripture.
Being fair also, even someone who is tuned in to Spirit, may experience "noise " within because of the nature of distractions and emotional noise by virtue of living.
Was this a warning in the New Testament? Well this question is very interesting and I have researched it as thoroughly as I can scripturally and historically.
Basically back in the ancient of days, there were those who deceived and didn't practice sincerely with God as co-creator in shedding light with others. So getting clarity by was of strong intuitive insight, with vision or without, got a bad wrap. Sorcerrer's and Warlocks and various magical types who were on the darker side made a mess of it for workers of the light. There's the historical side in a nut shell.
Again in these days and times, to be fair, there are those who practice white magic, and don't allow their egos' to get the better of them by practicing black magic. Bottom line. Here serious confusion sets in: Follow the Spanish Inquisition, and the Witch Hunts, and most famous story of Joan of Arc. The innocently accused.
Scriptually ... many people men and women shared their prophet gifts, insights and wisdom. Paul in the New Testament said, after being asked what gifts we should pray for said " The gift of prophesy, that all may be edified, one to another "... it's in Ephesians. I don't think he was thinking of evil people using their gifts or fabricating these gifts to the abuse of their fellows of mankind.
I do believe that each person possesses some form of the Intuitive, be it Clairvoyant, a Medium, or an Empath, as each one has special gifts. All people have some sort of impressions go off, but it's the degree to which we experience these things, some more than others, but ALL people should be respected for something that is natural to our spiritual selves.
So that you have an idea of what these three gifts are about (and there are more than these 3):
Clairvoyants usually have very strong impressions that express themselves in mental image pictures, sometimes fleetting fragments, sometimes whole and clear...like a tapestry.
A Medium is one who can pierce the Veil between life and life on the side after death. Often has images and can perceive of language, like words, and phrases.
Then the Empath is one who can perfectly duplicate others emotions, they pick up on people's feelings without even trying, this gift is meant for the healing of others.
The last question is...if you read cards (the tarot) then you must practice witchcraft. Actually no. The Tarot's origin is widely disputed, some believe it started in medival France, to act as code for various christian groups who could not openly practice their beliefs.
Others believe it originated a long time ago in Egypt, and possibly even further back, to Jewish mysticism, using the Kabbalah's...Tree of Life as the basis for mapping out one's spiritual journey on this Earth.
I believe in these times there are many interesting interpretations and none of it has to do with witch craft. It is us, WE are the one's who attach meaning to "things" like cards. But like the Oracle of ancient Greece, these tools help to spark off our Intuitive senses.