American performance coach Mary Spillane - previous clients Presidents Carter and Reagan - said principals and lecturers needed a strong personal brand image.
She told the Association of Colleges' annual conference that the image of college staff had not always been associated with style.
"The 21st-century lecturer should project both confidence and style and look like a man or woman of the future rather than someone stuck in a time warp. Learning how to dress to flatter yourself, project what you want and look modern is key," she said.
Principals lived in a world where people made snap judgments about others in just 15 seconds, which could take a lifetime to shake off.