Before launching into a traditional introductory paragraph with a thesis at its end, many writers open with the problem they hope to persuade others to remedy. To ensure this kind of direct opening will make your audience want to continue reading, avoid scolding, stick to the facts and keep it brief. For example: "The University of Michigan at Ann Arbor has an enrollment of 30,000 students, 20,000 of whom have cars. Every year, the university issues parking permits to all 20,000 students, but there are only 10,000 student parking places, which creates traffic jams, often makes students late for class and aggravates everyone."
Rather than open with the problem, open with a solution, which is a more optimistic approach, but one that calls for the other shoe to drop. For example, you announce that many fresh foods are now available to your school cafeteria through local farmers and food cooperatives, and you describe how with them, the school could improve child nutrition. Then you let the other shoe drop in the next paragraph in which you describe the problem: There's an epidemic of childhood obesity in your community, but school administrators are worried about the cost of fresh food, and the kids want their frozen pizza.
A startling statistic always commands attention. Start the opening with one sentence that states a statistic related to the focus of your essay. You may end the first paragraph there and move on to the next paragraph, or develop it with another sentence or two in which you give the reader some helpful background. Trustworthy sources include government agencies such as the FBI and the Census Bureau, and university studies. To use a statistic in an honest fashion, avoid mining the data; that is, don't take a statistic out of context or without regard for conflicting evidence. Always cite the source of the statistic to lend credibility to your opening.
Illustrate the problem with a strong image instead of an explanation. This appeals to the reader's empathy. To do this, think in terms of who, where, when and what, and be descriptive. For example, perhaps you want to persuade your elected representatives to vote for public funding of stem cell research. You might open with a description of someone waiting for a liver transplant. Describe the hospital bed, the person in it, the patient's yellowed skin and other concrete details. At the end of the paragraph, mention that stem cell research could make it possible for doctors to create new livers rather than wait for organ donations.