Browse newspapers and magazines, listen to the nightly news or consult books at the library for topic ideas. Avoid topics that are likely to have a built-in bias, such as abortion, animal abuse or drug control policies. Sources for these topics are likely to be for or against the issue, and these topics also have the extreme disadvantage of having been written to death. Look for human interest material, something that will bring new information to your readers or peek their curiosity.
Gather as many facts as you can about your topic. Use reliable resources such as government websites, peer-reviewed journals and professional publications. If your topic seems to have two sides, present material that covers more than one point of view. Be sure to make note of copyright information as you take notes, and associate your notes with title, author and publisher; it is much easier to write citations if you know where you got the information.
Sit down and write out all the things you know about your topic as quickly as you can, without stopping to check your data, grammar, spelling or structure. Read back through what you have written, and underline the most important points, the things you need to support with data, and any questions you may have about the topic. Use this "pre-writing" to guide further research or to create a data map or outline.
Write your main points or important pieces of information on sticky notes or small note cards. Spread them out and sort them to see which ones go together. Move them around to see what connects with what. If you have a mind mapping program in your computer, type your main points into it and use it to move the data around.
Use your data map and your pre-writing to create an outline for your expository essay. An outline will help you present your points in an orderly fashion, and keep you from telling about something, then having to backtrack and add prerequisite information. A good outline will cut down on the number of rough drafts you will have to write to develop a good essay.
Write the body of the essay first. Then go back and write the introduction and the ending. This may sound a little backward, but one of the places new writers get stuck is writing and re-writing their introduction. Often, if you write out the meat of your message, the introduction will almost write itself. The closing should simply wrap up the main points of your presentation.