Introductory paragraphs are hard. I always found that writing was easier once that paragraph was done and over with. The reason for that is the introductory paragraph guides so much of what is to come.
Your first step for any essay or paper is a thesis statement. That's the main point that you are going to write about. Figure that out before actually writing your introduction. You have a good start, because you have a narrow topic. What about Abigail's character do you want to focus on? Thinking about the play, I would aim your thesis toward making a claim that it is Abigail's love for John Proctor that causes her to continually accuse new victims. If that doesn't sound like the direction that you want to go, try a different thesis topic. Perhaps make the claim that Abigail's accusations and devious manipulations are representative of her power hungry nature. Whatever your thesis statement is, that is your last sentence of the introductory paragraph.
Your first sentence is the "attention getter." It needs to grab your reader's attention right away. If your first sentence doesn't do that, your reader doesn't want to continue reading. Don't give yourself a headache trying to come up with something amazing. There are five types of attention getting statements that are just about guaranteed to work.
- Ask a question. "Who is Abigail Williams?" or something like that.
- Make a bold statement of opinion. "Without Abigail Williams's influence, far fewer people would have died in Salem."
- Use a definition (I think this is weakest of the five).
- Use a quote from the text.
- Tell a story (not so good for written essays; very effective for speeches).
In between the attention getter and the thesis statement try to include some brief details that give your reader an overview of the plot of "The Crucible." Also include something about Abigail, since she is going to be the focus of your essay.
That takes care of your introduction. As for the body, make sure each paragraph supports the thesis statement. That's super important.