The key to relating to your audience is shared emotions. Emotions come from shared beliefs, and shared beliefs come from shared experiences. Experiences --> Beliefs --> Emotions --> Actions --> Identity is a useful tool.
Basically, you want to emphasize that you've gone through the same experiences that your audience has, you agree with them, you feel how they do, and since all of that exists, you would like them to take a certain action (whether buying a product, signing up for an email list, voting for you, donating, etc).
In business, you experience a problem in the human condition, you believe that the problem is bad, uncomfortable, unnecessary, or otherwise needs to be fixed, you feel the pain of everyone else who has this problem with no solution, and you encourage them to act on that pain by purchasing your solution.