Research your topic so you are well-versed in the history of it, the major entities involved on all sides of the issue and the current status of the issue. The more knowledge you have, the better prepared you will be when it comes to write.
State the issue you are advocating clearly in an introductory paragraph. Give the general background of your issue and why the readers should care about it. Your introduction will provide a general outline for your essay, and the rest of the paper will provide details.
Provide added depth, background story and details about your cause in the body of the essay. As you explain a particular point, bring it back to the goal of getting the readers involved in your cause. For example, if you are writing on behalf of shelters for abused women, you could provide the statistics behind documented spousal abuse incidents in the country and then mention that women's shelters rely on the funding from volunteers to function.
Provide resources and citations for the facts that you use in your essay. Your piece has more legitimacy if you quote facts and statistics from known and respected entities in your field than if you simply give your own opinion.
Conclude your essay with an emotional appeal to the readers to emphasize the difference one person can make in the cause, either financially or through the devotion of time. Your conclusion should quickly review the issues you have already discussed and leave readers with a final statement to stick in their heads about how they can join your cause.
Include a page of references showing where all of your facts came from. Alphabetize it by last name of the original author. This can also give your readers resources where they can learn more.
Attach contact information that gives readers someone to call or talk to if they want to donate or join the cause discussed in the essay.