I think we need to differ between
"acting like a wastelander and not out of character on the daily playing"
Talking like a wastelander in the fallout universe, doing things that seem realistic for a wastelander aka non metagaming
and
"do things that have no real impact on the world and take place mostly in the phantasie of every participant"
travel around with a purpose and goal you set for yourself like a caravan from town A to town B and enter every encounter.
Or place your things to trade on the ground and offer them as a merchant, hire guards who shoot looters etc.
Many people RP the first way, and thats totaly ok and easy to do.
But the real interesting and worthwhile things in my opinion are those little events, and by events I don't mean a big festival, just something you organize like a traveling merchant coming to a town and putting his items to display. But those things are hard to maintain and a sudden troll-airstrike can always happen.
What I also learned from past experiences is that if you have GM assistance, half of the people in the place are spamming "hi GM, gief skin plx".
