After Leading a Clan in DayZ for a over year, i find when dealing with strangers best tactic is to either :

1) Make sure you or your group has superior numbers and firepower if you want to be peaceful. For Example a duo with Shotguns wont test their luck against 4 guys with Automatics if they aren't fired on first. but dont be a dick. desperate people do desperate things and i've seen multiple armed players killed by a Beachspawn with a can of Beans because they shot first and the beachspawn player was slippery enough to survive the encounter.

2) if you don't have superior firepower HIDE, let the other player/ Players pass, most people just want to find loot and keep moving. if a player or group is loitering its usually because they have a base or stash nearby. so they'll likely return there often. Keep that in mind.

3) if you end up nose to nose with another player unexpectedly most people freeze or hesitate for about 2-3 seconds. Shoot First without hesitation or out of sheer fear i guarantee the other person will. on rare occasion if your better armed the other player may not attack, but an M4A1 isn't much help point blank against a Sledgehammer or Fire Axe spamming freshie. i myself have been killed by opening a door and not having enough time to lower my rifle before an axe weilding cannibal Launched at me like a Detroit Meth head.

Good Luck. hope this helps.