Mary K. Greer has a good post on the subject of Tarot cards and skeptics' view of them and the people who do readings. What jumped out at me was the following quote from a mentalist who uses Tarot cards purely as theater props: "All YOU the tarot reader have to do is make your readings entertaining and the repeat bookings will flow in. In the end it is YOU not the cards who are doing the reading, never forget that."
I found this observation quite interesting, since it is the polar opposite of my own approach (and I would guess, of most other Tarotists'). During a reading I try to stay out of the way, to become as transparent as I can, in order to allow the cards to speak. My responsibility is to communicate what the cards have to say to the querent as clearly, honestly, and compassionately as I can, with an awareness of my own limitations and shortcomings.
Obviously, intuition plays an important role in any reading, given that the cards have multiple meanings. Depending on a number of factors, such as a card's placement and the other cards surrounding it, the Tarot reader must be able to discern the most relevant and appropriate interpretation. I also pay attention to the ideas or images that pop into my head while I read the cards. Therefore, cultivating one's own particular intuitive or empathic gifts, along with a lifelong study of the Tarot cards' history and symbolism, are required to give useful readings.
I've done readings for family and close friends, where I know a lot about them, as well as for total strangers, and oddly enough I find that it's easier in some ways to do a reading when I don't know anything about the querent and their situation. In the case of someone I've not met before, I don't have to worry about filtering out my biases or presumptions, and can simply focus on what I see before me in the spread. It goes back to the issue of transparency, and being receptive to the Tarot cards rather than imposing my own interpretations onto them. Ideally I am simply a conduit for the information conveyed by the cards. It is truly the cards, and not me, doing the reading.
I am continually awed and humbled by the myriad, rich insights a reading can provide the querent. I won't pretend to understand how the process of shuffling cards and laying them out upon a table can produce a coherent, meaningful reading. I have had numerous experiences during a reading when the cards came together beautifully, each one supporting and elaborating the other. Arthur C. Clarke famously observed that "Any sufficiently advanced technology is indistinguishable from magic." The limits of my own understanding of the principles underlying the universe that is the Tarot only spurs me to continue learning and exploring this remarkable creation.