As the play opens, Abigail is arguing to defend herself against being put out of the house. She has no immediate family in Salem and relies on her uncle, Parris, who fears that her reputation is tainted and that this will ruin him. He doesn't want to "go down with her", so to speak.
She is essentially powerless to stop him if he wants to get rid of her. To stop this from happening and to deflect attention from her actions in the woods, Abigail quickly and geniously adopts the role of the victim. She begins to accuse others of witchcraft and in doing so takes attention away from her own actions and distracts Parris from his possible intentions of getting rid of her.
You can find quotes relating to these ideas in the first act of the play, such as when Parris says to Abigail:
...is there any other cause than you have told me, for you being discharged from Goody Proctor's service? I have heard it said, and I tell you as I heard it, that she comes so rarely to the church this year for she will not sit so close to something soiled.
Abigail empowers herself by using sex to control people. She has an affair with John Proctor, and uses that to try to influence him. As a servant, Abigail does not have any power over her life. Her reputation is damaged because Goody Proctor fired her when she found out about the affair.