Research your paper's subject, and formulate your paper's argument based on your research before you start writing. Your research will help you decide what you want to state in your paper and how you want to organize the material, all of which you will summarize in the introduction. For example, researching Shakespeare's female characters will help you draw a conclusion about how Shakespeare characterized the women in his plays.
Develop the research paper's thesis statement, and clearly express the thesis statement in the introduction. The thesis statement identifies the point you will make in the paper based on your research. Make the thesis specific, taking a position. For example, the statement, "Shakespeare developed flat female characters that created the struggles of the male protagonists" takes a specific position about female characters in Shakespeare's literature.
Summarize supporting points from the remainder of your paper in your introduction to explain how you arrived at your thesis. Although the introduction appears first in a research paper, you don't have to write it first. Write the body of your paper based on your thesis first so that you have clear direction of what to write in the introduction. For example, a statement in your introduction such as, "Lady Macbeth's ambition spurred Macbeth to kill the king, thus creating conflict," would summarize the section of your paper that discusses the characterization of Lady Macbeth. Because you will make several points in your paper, expect to summarize several points in your introduction. Be brief in your supporting points because you will go into detail about them in the paper's body.
Attract your reader's attention. Use the introduction to get your reader excited about your paper's subject matter. Use a quote, fact or humor to grab the reader's attention. A line from one of Shakespeare's plays regarding women would engage a reader and make him interested in reading more.
Edit and revise your draft of the introduction. The information in your introduction doesn't have to be in a particular order, but it must be coherent and flow logically from sentence to sentence. Read and re-read your introduction as if you read it for the first time. Don't hesitate to have someone else evaluate your introduction to ensure it makes sense, is interesting and clearly states your argument.