Before you argue, find out what you agree on. It makes the disagreement smaller and easier to win.

Most disagreements are far narrower than they feel. Two people shouting about a curfew usually agree on almost everything and differ about one hour on a Saturday. Naming the common ground shrinks the fight to its real size and makes the actual difference obvious. It also stops the other person defending things you were never attacking.

Open the next argument by saying what you agree with, out loud and honestly. Then put the one point in dispute into a single sentence. Shorter arguments are the ones that end in a decision rather than a mood.