Datalex persona boards
This is a methodology that I've been refining as a Group Creative Director over the last few years. Essentially they are persona boards intended to help clients and their agency partners develop a profound understanding of their target audience. All of the audiences portrayed are perfectly legitimate yet distinguishable enough that the manner in which you communicate with them would vary greatly. The idea is that once we have decided on our target we all put these up on our walls and refer to them often to keep us focused and authentic in our communications.