Worthwhile argumentative topics are either timely or timeless. Timely topics concern current events. Election issues, whether representatives should pass a new law and the cause of a viral outbreak are timely topics. Next year, they will be settled. But timeless topics concern issues that people never completely settle because they have strong feelings about them. For example, people never lose interest in discussions that concern freedom of speech, the meaning of religious freedom and medical ethics. Within them, many subtopics represent good argument material. However, some subtopics of timeless issues are stale. If you want to debate sports ethics, for example, think twice about choosing steroid abuse unless you can bring new insight to the subject.
Every issue worth arguing has two sides. No matter which side you are on, it is imperative that you carefully examine both sides. Writers and debaters who ignore opposing arguments leave holes in their presentations, and thus cannot effectively make a convincing case. The audience wants to know that you have thought carefully about both sides and that you can refute counter-arguments. Remember that argument is more than presenting an opinion, it also embodies rebuttal. Additionally, addressing both sides of an issue is a question of integrity. Addressing both sides increases your credibility, puts your argument in context and inspires an audience to trust your point of view.
To lend weight and credibility to your position, develop a strong argument that cites authoritative sources. Scholarly research, quotes from relevant experienced professionals, census statistics, FBI statistics and legal citations all represent authoritative sources. The writer or debater must use authority sources in a fair and honest manner, meaning you should not use them without explaining the context or in any way that misrepresents the truth. It's best to draw from accurate recent sources, rather than dated sources.
Even if you are developing an argument to support a worthy cause, logical errors can destroy it. For example, if you assume that one event caused another because the second followed the first, you are guilty of the false cause fallacy. It is not necessarily true that an event was caused by another event immediately preceding it. Sometimes it's just a coincidence. In an example of another fallacy, if you assume that all drum players are alcoholics because every drummer you've ever seen is an alcoholic, you have made a hasty generalization, also a logical fallacy. There are many kinds of fallacies. As you write or debate, the more aware you are of fallacies, the better your argument will be.