I'm relatively new to DayZ, and decided to adopt a friendly/survivor approach, so far it has worked out for me. Last night I had my first really successful run in a 2-man team with a buddy. We were able to talk our way out of 3 different encounters with other survivors, 2 of which we were outnumbered, and 1 with an actual bandit. Generally I just try and get away as quietly as possible if I see another player, but if it's impossible, so far the shouting "friendly" approach has seemed to work, especially if you offer some advice with it. All of the encounters I got into would have ended most certainly in death if I had gone KoS (though I understand for some people that is "fun").