Be successful.
Men's attractiveness is very directly tied to their competency, and the reason is because female species throughout existence, has always been looking for sexual partner that can provide protection and resources (maximum chance of survival) for themselves and their offspring. In the modern sense, it means men that are successful in life. Unfortunately, unsuccessful men resent such sentiment and label women who exhibit such tendency as gold diggers, some women are definitely guilty of this, but men are just as guilty of being shallow (desiring attractive women that exhibit qualities that can give birth to the healthiest offspring).