@all of you that have some experience with Warpg-ey gaming: what was your best/worst/other experience at introducing this kind of -at least- less competitive gaming in your group?
Any best practices, do's or don'ts?
For me, it was really easy to introduce my friends to this kind of gaming, as most aren't as familiar with miniature gaming as they are with role-playing games. A major do (which you already know, having read the posts) is not to be too strict with the rules. New players especially will want to do special stuff fairly often, and in my experience it's much more fun to make up things ("Sure, you have to roll 4+ to climb onto the roof") than shoot ideas down ("No rules for climbing, sorry"). Also for newer gamers, you can throw in simplified mechanics as I did in this one:
https://dawnofthelead.com/2015/11/01/halloween-fun/ . It's basically a very simple, competitive game of collecting points, but while the players are competing against each other, now direct attacking is allowed.
In my Utopia campaign as well as other games, I tend to give people several characters. That way they're not too stressed out about their only character dying, and allows for fun interactions. Here's a take from one of my friends:
http://dustygamer.mcmuumio.net/2013/troupe-play/ - it's a great post and I strongly suggest reading it!