Choose Models That Resemble Each Segment

People in ads are more effective when they resemble customers.

Three different segments: nerdy middle-aged type, young sporty type, older female type

Overview

Advertising via Facebook? Instead of displaying the same ad to everyone, replace the model with someone who resembles each segment.

...when consumers are exposed to advertising that is consistent with a salient dimension of their self, they spontaneously self-reference the ad. This leads to more favourable thoughts, attitudes and purchase intentions (Lee, Fernandez, & Martin, 2002, p. 374)

You could segment on a broad trait, like gender. Or create tighter segments by focusing on psychological characteristics.

Lee, C. K. C., Fernandez, N., & Martin, B. A. (2002). Using self-referencing to explain the effectiveness of ethnic minority models in advertising. International Journal of Advertising, 21(3), 367-379.