"The cloth upon which the lots are cast should be made of white material. Not only does Tacitus indicate this in his report, but this practice is borne out by the symbolism of white as a sign of the undifferentiated sum of magical light. It is upon this white field that the runes play out their interweavings of force. The cloth itself should be made of linen or some other natural material, and should be between three and four feet square." At the Well of Wyrd - Edred Thorsson.
Thorsson also states that "For practical reasons, most runecasting will probably be carried out indoors, in your living quarters. For ritual effectiveness other runework should be done in the same area. One advantage to runecasting is that the vitki can carry the basic 'holy stead' around in the form of the white cloth. However, for especially important castings other holy steads might also be considered. Most beneficial are sites under holy trees-oaks, breeches, yews, ashes-or near (south of if possible) a natural spring or an artificial well. Hilltops are also good places to do runework. Outdoors, the runecaster can follow the rede of the ancient tradition more effectively and look into the sky when picking the staves for the reading. The force can be especially powerful at night if you look directly to the Northern Star-into the eye of Odhinn-while choosing the lots."