Choose a unique topic. Nothing is more off-putting for instructors than reading the same paper semester after semester. While you may feel strongly about abortion, war or gay rights, unless you are presenting a completely new approach to the argument, someone else has already done it many times. Consider a topic many people may not have covered already, or something you are interested in but do not feel you know enough about.
Compile effective and comprehensive primary and secondary sources. Having effective sources from which to cite in your persuasive paper is incredibly important to validating your argument. Because you are most likely not the foremost expert on the topic, search out who is and quote from that person. He or she has most likely spent years researching and analyzing the topic so put that expert's hard work to good use. Blogs or social networking cites tend not to be the most reliable sources. Neither is any Wiki-oriented site.
Recognize all sides of the argument in your paper. There is a reason you are attempting to persuade your reader to your side of an argument -- because another side exists. By recognizing the validity of other arguments writers do not undermine their own position but strengthen it. Allowing that there are reasons not to neuter animals -- but then counter-arguing with even stronger arguments for neutering -- shows the reader you have looked at the problem from all angles, and the position you support is the most logical.
Organize the paper in an effective manner. In high school, the assignment may call for a five-paragraph essay. To structure the five-paragraph essay, use the introduction to introduce the argument. Paragraph two should explain the argument you present. Paragraph three should recognize alternate sides. Use paragraph four to refute said arguments, with the final paragraph summarizing what you have discussed thus far. For a college essay, five paragraphs will most likely not be long enough for the assignment. Following the same order for the high school essay, create two or three paragraphs that explain all the reasons for your position. Likewise, present two paragraphs of counter-arguments and two more paragraphs to refute those arguments.
Create effective and comprehensive opening and closing paragraphs. The introduction is imperative to convincing the reader of your side of the argument. The opening paragraph contains the thesis statement, which is the argument you mean to present throughout the paper. Similarly, the closing paragraph is with what you leave the reader. A bland conclusion suggests to the reader that even you are not convinced, or even very excited, about what you have just spent the last few pages discussing. A conclusion should allow the reader to comprehend how you have presented and proven the argument presented in the thesis statement and opening paragraph.