It is both good and preferable to throw the dice on a non-skid surface, such as a rubber mat, a piece of fabric with a nap to it (such as felt, velvet, suede or fur), or a sheet of craft foam, which can be purchased inexpensively at a fabric store or craft supplies store. You want to minimize skid. I like to draw the circle with some kind of ‘puffy’ kind of craft glue, which serves as a barrier to keep the dice from rolling out of the circle.
I keep my dice in a special cup for use when casting. Three dice used are traditionally used for dice divination, and the traditional answers number from one to eighteen. If you have only two dice, you throw the dice twice to get an accurate reading.  One die, you’ll have to throw it three times to get an accurate reading. When I purchased my dice, it came in a pack of five. You can discard the extra two dice or give them to a needy friend and use only three, but if you choose to throw all five dice, I have included additional meanings beyond the traditional eighteen in the interpretations which follow. The meanings for the throw-results nineteen-through-thirty are based on the meanings the ancient Chaldeans assigned to those numbers, and personal experience.

Predictions the dice make are said to come true within nine days, so it’s recommended you dice-divine no more than once a week. Attempt no more than three throws in a dice divination session. If, in three throws, all the dice land outside the circle, then the Spirits either don’t have a message for you or don’t want to communicate with you at that time for reasons known only to Them. If this is the case, accept it and try again next week.