Choose what you will write. While the topics are often picked in advance, giving you no say in the matter, there are instances where contestants can choose a topic within a given subject. You may even be given a choice between a limited number of topics.
Research your topic. If you are given choices as to your topic, you will want to do research on all the choices to determine which is the best topic for you. The internet is excellent for research purposes Even if you aren't given a choice, you will still want to do your research to gather as much information as you can.
Plan in advance. Essay contests have fixed, not flexible deadlines, so you will need to plan carefully ahead so that you don't procrastinate and end up being disqualified. Set a schedule, a certain time each day when you will work on your essay.
Decide from which angle you will approach your subject matter. While it is important to stick to the given or chosen topic as closely as possible, you want your essay to stand out, not sound just like everyone else's. Unless you have something new to add, avoid the conventional perspectives and go for the unique, You can use your research to brainstorm for ideas. Keep a notebook and pen handy in case an idea hits and you're not near your computer.
Outline in advance. Even experienced writers need to do this. Organize your main topic for each paragraph, along with subtopics within the topic. That way, you will have a concise and organized essay.
Use plain language. While you might be tempted to impress by using big words, remember that the most important thing in writing a strong essay is clarity. Avoid wordiness and filler phrases. Each sentence should be understandable and move your essay forward.