Abigail chooses early on to reject Mary Warren's idea to confess to what went on in the woods. Mary Warren suggests that the girls admit to dancing in the woods to avoid a severe punishment.
Abigail, who has a very untenable situation in Salem, rejects this course of action, choosing instead to attempt to deflect attention from the girls onto others in town. This is why she begins to say that other people had sent their spirit out (in acts of witchcraft).
This is arguably the most important choice Abigail makes in the play. Later, she also chooses to frame Elizabeth Proctor. This act is important to the play as it enmeshed John Proctor in the trials and sets his path toward the gallows, creating the drama of the last two acts in the play.
The decisions made in the first act are more significant to the town as a whole. These decisions are motivated by Abigail's weak position. She has been fired from the Proctor house and now lives under a cloud of suspicion. Parris discusses the rumors with her in the play's opening scene.
Abigail has no parents in Salem and is dependent on her uncle, Parris. Parris is willing to cut ties with Abigail if she threatens his own position in the town and he makes this clear to Abigail.
This dynamic is part of Abigail's initial motivation to begin accusing people of witchcraft.
Betty stated that Abigail drank a charm in order to kill Elizabeth. Abigail’s actions towards Mrs. Proctor were motivated by the fact that Abigail and John Proctor engaged in an illicit affair. Elizabeth found out about the affair and had Abigail sent out of the Proctor home. John apologized for the scandal and got over the relationship, but Abigail insisted on maintaining the affair. During the witch trials, Abigail directly implicated Elizabeth in witchcraft through a poppet made by Mary Warren.
Hale questioned Abigail and Tituba about what they did in the forest and when Abigail was cornered by Hale’s questions she blamed Tituba. Abigail claimed that Tituba made her drink some blood and practiced witchcraft. Abigail’s motivation was to preserve her name in the society. In addition to blaming Tituba, Abigail implicated some members of the Salem community in attempts to deflect attention from the girls and their actions in the forest.