It may be helpful to understand the debate techniques that people often use. This web site lists all the illegitimate tactics that people tend to use.
http://www.don-lindsay-archive.org/skeptic/arguments.html A few examples are listed below:
Straw Man (Fallacy Of Extension): attacking an exaggerated or caricatured version of your opponent's position.
For example, the claim that "evolution means a dog giving birth to a cat."
Another example: "Senator Jones says that we should not fund the attack submarine program. I disagree entirely. I can't understand why he wants to leave us defenseless like that."
On the Internet, it is common to exaggerate the opponent's position so that a comparison can be made between the opponent and Hitler.
Argument From Adverse Consequences (Appeal To Fear, Scare Tactics): saying an opponent must be wrong, because if he is right, then bad things would ensue. For example: God must exist, because a godless society would be lawless and dangerous. Or: the defendant in a murder trial must be found guilty, because otherwise husbands will be encouraged to murder their wives.
Wishful thinking is closely related. "My home in Florida is six inches above sea level. Therefore I am certain that global warming will not make the oceans rise by one foot." Of course, wishful thinking can also be about positive consequences, such as winning the lottery, or eliminating poverty and crime.
Excluded Middle (False Dichotomy, Faulty Dilemma, Bifurcation): assuming there are only two alternatives when in fact there are more. For example, assuming Atheism is the only alternative to Fundamentalism, or being a traitor is the only alternative to being a loud patriot.
False Cause: assuming that because two things happened, the first one caused the second one. (Sequence is not causation.) For example, "Before women got the vote, there were no nuclear weapons." Or, "Every time my brother Bill accompanies me to Fenway Park, the Red Sox are sure to lose."
Essentially, these are arguments that the sun goes down because we've turned on the street lights.
Moving The Goalposts (Raising The Bar, Argument By Demanding Impossible Perfection): if your opponent successfully addresses some point, then say he must also address some further point. If you can make these points more and more difficult (or diverse) then eventually your opponent must fail. If nothing else, you will eventually find a subject that your opponent isn't up on.
This is related to Argument By Question. Asking questions is easy: it's answering them that's hard.
It is also possible to lower the bar, reducing the burden on an argument. For example, a person who takes Vitamin C might claim that it prevents colds. When they do get a cold, then they move the goalposts, by saying that the cold would have been much worse if not for the Vitamin C.