Be open and honest about what works and what doesn’t
Some people don’t like the term “test-and-learn” because this makes it
sound like the experts in the marketing department aren’t so expert
after all.  Actually, nothing could be farther from the
truth.  More and more, marketing is becoming a science.  And
as scientists, it makes sense to build experimentation into what we do.

Some tests are fielded to validate what we think we know about
customer behavior, others because we don’t know how specific customers
will respond when presented with a particular message, offer, or value
proposition.  What is critical is to build a knowledge base of the
learning accumulated through testing and make that knowledge available
throughout the extended marketing team. The knowledge base you build
does not have to be based on specialized software for either knowledge
management or marketing performance management.  We find that what
works best is a system that is simple and makes knowledge available
throughout your company and across the extended team, including agency
partners.

In building the processes you’ll use to manage marketing
performance, be open and honest about what has and hasn’t worked. 
In the book, “How Customers Think”, Professor Gerald Zaltman points out
that much of what we think we know about customer behavior is flat-out
wrong.  Customers are not rational, linear thinkers and often
behave in ways that are entirely irrational and even random. 
Marketing professionals do themselves a disservice by not being upfront
about their inability to predict how customers will behave.