Dice play calling 'how to' question....

[Drk]

Question for those who use dice to call plays; how do you set it up?

How many dice? How do you number the plays? Do you allow for the probablility of different results (when rolling two die 7 is the most likely outcome while 12 & 2 are the least likely).

I know some use nontypical dice; say a 20 sided. But if you use that for 20 plays all plays equally likely to be called.

How do you account for different situations such as third and long vs. 4th and inches?

How do you use dice to call defenses?

There are just so many variables. I have some ideas but I don't want to spend a lot of time reinventing the wheel here.

Thanks in advance for your input.