Be charitable when you teach other people. As soon as you lose charity, you lose the help of God's grace. If God so willed that you should debate or talk about a topic of the faith, he will be on your side so long as you are charitable.
2. Is your opponent uncharitable? Don't Debate
Such people are too deep into their emotions to debate. Catholics must only debate with people who are prepared with reason and sensibility.
You may calm your opponent down, by telling them things slowly, listening to them, and taking it one step at a time. But if this cannot happen, the debate should end, and keep your peace.
3. Debate using a common belief.
Don't try to prove to a protestant by making reference to the Catechism of the Catholic Church. Why? Because that is not proof to a protestant. However, you may make reference to the bible, because that is a common belief between you and your opponent.
4. Really, is your opponent too patriotic to change his views?
If he is really stuck into what he believes in, it's no bother. It's better to end on a good note, and leave it to the grace of god to change him.
5. Your biggest proof is your charity.
Don't be silly, don't show hatred, don't show lack of sincerity. Make sure when your opponent leaves, that he can accuse of everything, but he cannot accuse you of lacking charity.
Hope this Helps.
Be Charitable! Share with your fellow debaters and apologists.