Ask three questions before engaging in any conversation:
1) Do you both agree on the purpose of what you’re arguing about?
For example, if engaging in an argument about government policy, do you both agree on what the purpose of government is? If you don’t agree on the purpose, you’ll never sway each other as you’re arguing two different things.
2) Can I change this person’s opinion?
Is the person the type of person who makes decisions based on logic and reason, or are they ruled by emotion? If they’re ruled by emotion, no logic or reason, no matter how sound, will sway them. Try literally asking them “what could I provide that would sway your opinion?”
3) Will I benefit if this person’s opinion is changed?
Let’s say you succeed and change the opinion of a random dude on the internet… and? What did you gain?
4) Am I prepared to listen and have my opinion changed?
If any of these 4 questions can be answered with a “no”, do not engage in the discussion.
You will find this process will cause you to avoid most arguments.