Is there some system to making the circle or you just lay them out randomly?
I think there’s a book on this, by Donald Tyson.
I have never done this, nor read any book on doing this so take what I say with that in mind (and pick up Tyson’s book on Tarot Magic if it interests you, I suppose).
A magical circle represents your understanding of the universe (and your place in it). Consequently how you would lay out the tarot for it depends on your worldview. I can conceive of numerous ways to lay them out that would be applicable, perhaps depending on what you looked to achieve.
I find laying them out randomly a bit blasé, however, if you hold a worldview that your life and the universe is entirely random and chaotic then that may very well be appropriate.
If instead you came from something akin to a Golden Dawn perspective you might lay the cards out in order of their “manifestation” down the paths of the tree of life, essentially representing the process of incarnation of God on earth (as you, in the center).
If you hold any semblance of an astrological worldview you might approach it in that way. For example, by laying out the cards corresponding with the zodiac around you, starting with Aries (The Emperor) in the east and placing each counterclockwise in order, Taurus (Heirophant) etc. You could even personalize this and start with your own rising sign in the east, your planets in their places, or “turn it” around if you were doing work in particular areas of your life.
Another astrological approach (especially for more “mundane” magic) would be to use the decans of the cards in their order, which would use the minor trumps instead of the majors. Thus starting in the east following along in this order (counterclockwise) http://www.tarot.org.il/decans.html
If you were approaching it elementally you may lay out the different suits in their appropriate direction in their order.
Eh. I was going to use the Tarot circle to evoke a spirit while I sit in the UC. Maybe I will just use playing cards.
May have to look at vampire tarot.
Get something like a bamboo cane about four feet high. put a thinish nail in the top and a platform of some description on the floor to stand the cane upright. Plasticene is good for the aforementionned. Now get some cardboard it should be the few mills thick stuff with corrugated interior - cut a little bigger than the tarot (angels or demons tarot) and stick pictographic images on the cardboard bits - then stick them onto the nail so they stand straight up. Very effective way of calling the quarters as you have pictographic images at chest or eye level even.
Any variation for the same effect is conducive.