We are not great at this - but a few thoughts:

Keep disagreements in perspective. Don't let a toilet seat up/down arguement turn into a major fight. Don't insist on winning an arguement just to win.

Don't go nuclear. I fthe disagreement is about turning off the upstairs lights, don't let it evolve into an arguement about the entire relationship.

Don't re-open old issues. If someone was flirting with a co-worker at a company party, don't bring up a long-ago breakup over someone neither of you has seen on 20 years.

Remember that you will not agree on everything.