Answer:
By serving on Roman advisory boards outside the realm of normal government.
Step-by-step explanation:
While women had an inferior social and legal status in the Roman Empire, and could not hold formal political power (could not serve as senators, or consuls), they did have some political spaces where to excercise influence.
These spaces were informal in nature: advisory boards, or even parallel institutions, were established sometimes, and in these spaces, women could share their opinions, and influence the political decision process. However, it must be clarified that this influence was still marginal when compared to the influence that men had.