Think of topic relating to aspects such as abortion, homosexuality or death sentence. The basic thing about what you intend to write on is that it should in itself bring in some argument. If a topic is decided for you or you are to decide on topic, there should be nothing different. What you need is to have all the materials that are needed to buttress your facts and support your evidence.
You should start by letting the reader know what you hold as true about the topic. It will also be good if the readers know what is generally thought about the topic. This should be stated in one statement. In writing this statement, you should also know that it needs to generate so much argument in the same way as was reflected in your main topic. For a more precise essay, your topic and your main statement should be narrow enough. Keep in mind that an argumentative write-up is almost unending and writing on something unending would seem an uncertain pursuit and even an overwhelming drudgery for you. For example, in writing about death sentence, you may decide to limit yourself just to the humane part or religious part of it. Sometimes it is necessary to pick out just one aspect of the whole topic and argue about it, rather than including a whole lot of points and just surfacing on them.
Argumentative essay should be concluded by making a reassertion of your position. This position should be such that renewed arguments will prop up. Ahead of stating this, you should sum up all your evidence and remember that your evidence must pass the necessary tests. Your evidence should be truthful and straight to the point; it should be consistent with your facts; it should be up to date or even the most recent; it should be representative of what it intends to prove; it should not be oversimplified and it should be ample and sturdy enough to back your assertions and plead your case to the readers.