Verify that your thesis statement is clear, concise and firm before writing the introduction, because the thesis should conclude your introduction. Write the introduction prior to the research paper, during its writing, or after writing the research paper, as best suits your needs. Unless writing a lengthy dissertation, the introduction should be approximately half a page or one to two paragraphs long.
Grab the reader's attention with a fact, question, quote, analogy or short, interesting narrative supporting the thesis. This should set the tone for your paper while triggering the reader's interest in the subject. Spend time and effort on this part of the introduction, because it may be the key in convincing the reader to read further.
Write statements that provide general background information about your thesis in the introduction. Use information that may generally be common knowledge but that clarifies the subject of the thesis. These statements provide a point of reference for the reader to help him understand the thesis.
Provide statements that become increasingly specific as you write this paragraph leading to the thesis statement at the end of the introduction. The statements should provide information about the points to be made within the body of the paper concerning the thesis.
Throughout the introduction, state the main points that your paper will cover regarding the thesis without going into detail. These points provide further framework and organization clues for the reader that help him understand your paper as he reads it. They also provoke questions in the reader's mind, causing him to want to read further. For example, if the thesis statement concerns the advantages of free, public prekindergarten education, then the points that organize the thesis research may include developmental needs, societal needs and available funding sources.