P is for Practice
Because there is no such thing as Best Practice.
Every Brand, Business Model, Audience combination is unique and as a result you have to create your own Best Practice.
And you can only do that by creating and sticking to a good Test, Learn and Refine programme, remembering that the world of audience engagement is ever changing so models you created six months may no longer hold true.
Also remember that all models are flawed; it’s just that some are more useful than others. Gravity is a law, expected open rate is not
As Lee Trevino the famous golfer highlighted, the more you practice, the luckier you get.