If a rational ethical egoist advocated principles of conduct to the general public what kind of principles would they be

Act in their own self-interest.

Explanation:

Ethical egoism has as core value the own self-interest. Through this theory, it's considered ethical when the actions taken benefit the individual, not considering others benefits at all.

A rational ethical egoist would advocate for people to pursue their own interest for it is in pursuing our own interests that we contribute to the advancement of society. Progress in human society lies in people pursuing their own interest and in competing which has resulted in innovations and technological development,