These two women, we learn, are quite cunning and devious, along with a bit hung up on some old issues that they are having a hard time letting go of. They are also more guilty of witchcraft than anyone who gets accused. At first, Mrs. Putnam come off as a god-fearing woman who is overly concerned for her sick child, Ruth. But as act one continues, we learn that she is fixated on the fact that she "laid seven babies unbaptized in the earth," and wants to find out why all of those babies died. Of course, she turns to witchcraft, and assumes that a witch killed her babies, so she sent Ruth to "learn from Tituba who murdered her sisters." So, Mrs. Putnam, obsessed with the death of her children, despairing in her grief, essentially asks Tituba to conjure up the spirits of her dead babies. That's witchcraft, right there. But, she does not get punished, and through their daughter, the Putnams lead many of the charges and arrests.
We learn pretty quickly that Abigail is not an innocent girl with a "white" reputation, as she claimed. She had an affair with John Proctor, and is so obsessed with him, even after he ended it, that she "drank a charm to kill Goody Proctor," hoping to get rid of John's wife so that she would take her place. So, she was drinking charms--witchcraft. She is also devious, threatening all of the girls that if they tell she will bring them a "bloody reckoning." She then turns on Tituba, when she sees a way out, blaming Tituba for all that happened, then naming other "witches," all so that she didn't get in trouble. Abby is the ringleader, the gang leader, the threatening and frightening, vengeful girl that, in this play, is responsible for most of the accusations that occur.
I hope that those thoughts help; good luck!