Accept the other person as a fellow human being. Ask questions. Discuss with facts and evidence-based position. Stick with the truth and the right. Come to an agreement with your opponent on a better solution to solve the problem your opponent is accusing you of.
Example: "Trump is racist, therefore you're a racist" Agree and let the individual know that racism or racial discrimination is disgusting. Present facts why racism never worked in any country ,and that, our Republican forefathers fought for the right of African-American slaves to be free and not be slaves. Trump is never racist and show why.
Having a discussion and a peaceful conversation is NOT about "I WIN" but it's about bringing about the good or best in the other person the ability to think for himself and enjoy his freedom available to him as a free-thinker.