Here might be a good place to start: http://www.startupcompanylawyer.com/2009/01/01/how-do-you-se... (this is a somewhat technical piece but written by a real expert in the field and aimed at the knowledgeable executive or other non-lawyer - the discussion of the old 10 to 1 ratio between preferred and common pricing, and the new ratio used since the enactment of IRC 409A, appears toward the end of the piece).