Do not play Mr. Williams like a confused old man.

That's extremely important.

He's eccentric.
He's unpredictable.
He can fall asleep without warning.
He says things that seem completely unrelated.

But underneath all of it is a sharp, experienced man who's been around long enough to understand people, money and mistakes.

The comedy should come from how seriously Mr. Williams takes himself, not from the actor trying to be funny.